Eastern Prickly Pear
Eastern Prickly Pear (Opuntia humifusa) is a cactus of eastern North America and it is the only cactus native to Connecticut. It is sometimes also known as Indian Fig or Devil's Tongue.
This cactus is only found in a limited number of locations throughout the state, owing to very specific habitat requirements and dispersal patterns that are only vaguely understood. Most often these cactus colonies are found along the coastal regions of Connecticut, but they can also be found in isolated locations on rocky inland ledges and forest glades.
I have confirmed the existence of six (6) colonies and two (2) complexes of O. humifusa in eight towns in Connecticut: Bridgeport, Guilford, Hamden, Milford, New Haven, Old Saybrook, Plainville and Stratford. My research has revealed that further colonies can be found in Branford, Darien and Norwalk, however I have not yet personally verified the existence of these colonies. Historic records suggest that O. humifusa colonies also existed in Beacon Falls, Burlington, Franklin, Naugatuck, Oxford, Scotland, Seymour and Wilton at one time. However, because many of these records are over 100 years old, the colonies to which they refer may no longer exist. For example, extensive explorations of Beacon Falls have yet to reveal the continued of existence of O. humifusa which was known to be common there in the late 19th-century.
Distribution in Connecticut[edit]
O. humifusa is extraordinarily fragmented in its distribution throughout the state, even in coastal regions where the concentration is highest. This generally characterizes the species throughout all of its range in the Northeast United States. Even as early as 1900, for example, an issue of Popular Science magazine erroneously speculated that three colonies of O. humifusa found growing on Hook Mountain in New York might be "either the descendants of a stray from cultivation or, perhaps, purposely planted there by some enthusiast".[1]
In most Connecticut towns where I have confirmed the presence of O. humifusa, the colonies are found only in very isolated locations despite the fact that they are in close proximity to similarly suitable habitat. For this reason, it seems highly probable that O. humifusa living in Connecticut are not especially adept at long-distance seed dispersal, instead relying largely upon vegetative reproductive techniques which promote colony health in the immediate vicinity but accomplish little in the way of range expansion.
Habitat in Connecticut[edit]
Although many species in the Opuntia genus have been widely and thoroughly studied throughout the world, much of this research applies only loosely to Connecticut populations of Opuntia humifusa. O. humifusa is exceptionally unique in its ability to live and grow much further north than the vast majority of other Opuntia spp. It possesses a number of special adaptations that allow it to thrive in Connecticut's environment such as, for example, an unusually high tolerance to freezing temperatures. These unique adaptations contribute to habits which are unique to O. humifusa and, in some cases, differ significantly from other Opuntia spp.
However, the situation is made even more complex by the fact that the far northern extent of O. humifusa's range in New England begins to taper off in Northern Connecticut. In other words, Connecticut represents transitional territory, from rather suitable habitat along the southern coast to entirely unsuitable (or nearly unsuitable) habitat in the far north. Because the range extent of O. humifusa tapers off within Connecticut, we are likely to see a number of peculiarities in Connecticut's populations that derive from the fact that some environmental needs are only barely being satisfied by available habitat and conditions.
O. humifusa can be found in two distinct types of habitats within Connecticut: 1) low-elevation, coastal, sandy scrubland and 2) mid- to high-elevation, inland rocky ridges. For as much as these two habitat types are outwardly different, they generally offer very similar climate conditions. Both habitats typically possess a yearly average temperature which is slightly higher than that of Connecticut as whole, they offer extended exposure to full sunlight, and are both xeric habitats that possess dry, well-drained substrate.
O. humifusa only persists in locations where several hours of exposure to direct sunlight can be obtained on a daily basis. A study of O. humifusa colonies in Ohio, for example, found that the cacti ceased to flower when subjected to shade by recent encroaching tree growth.[2] As such, the absence of shade trees and dense, fast-growing shrubs in the immediate vicinity of the O. humifusa colony is imperative to its health and continued existence. Thus, not all coastal scrubland or rocky ridges necessarily provide sufficient habitat.
Northern Range Limit[edit]
An evaluation of documented Opuntia humifusa colonies of New England and the Northern-Central United States (from earliest records to 1987) has demonstrated that the northern range limit of the species is approximately 42° N latitude.[3] There are a few reports of O. humifusa found living north of this line of latitude, but such reports are scarce and possibly erroneous, either representing populations introduced by humans or misidentification of other, more-northerly cactus species for O. humifusa.
The proposed northern range limit of 42° N runs just south of Connecticut's northern border, such that the state contains a transitional region where O. humifusa thrives along the southern coastline but is almost never found in the northern half of the state.
Temperature[edit]
Because temperature is widely acknowledged as a major factor in the ability of O. humifusa to establish itself in a particular locale, it is instructive to examine the location of known Connecticut colonies in juxtaposition with the United States Department of Agriculture (USDA) Zone Map of Connecticut. The USDA Zones Map shades various areas of the state based upon average extreme minimum temperature.
Zone 7a is warmest in Connecticut, with mean minimum temperatures of between 0°F and 5°F. The range of this zone in Connecticut is very limited, extending in a narrow band along western coastal regions of the state, as well as the farthest eastern coastline. Approximately 42% of the O. humifusa colonies I have observed (3 of 7 colonies) fall within Zone 7a.
Zone 6b covers most of the southern half of Connecticut and is characterized by a mean minimum temperature of between -5°F and 0°F. Approximately 42% of the O. humifusa colonies I have observed (3 of 7 colonies) can be found in Zone 6b.
Zone 6a covers most of the northern half of Connecticut, with the exception of the northwestern corner of the state. Mean minimum temperatures in the zone range from -10°F to -5°F. Only one colony, the Metacomet Colony in Plainville, falls within this zone.
Zone 5b represents the coldest regions of Connecticut, with mean minimum temperatures ranging from -15°F to -10°F. Only the northwestern hills of Connecticut fall within this coldest zone. I have not documented any colonies within this zone, nor have I found any historic data suggesting that O. humifusa ever lived there.
Although confirmed colonies of O. humifusa can be found in 3 of the 4 zones of Connecticut, the cactus clearly shows a preference for Zone 7a and 6b. Currently, 85% of the colonies I have photo-documented grow within these adjacent zones. Furthermore, if we include known colonies that I have yet to document, that number can likely be raised even higher, with as much as 90% - 95% of Connecticut's total biomass of O. humifusa growing within Zones 7a and 6b.
Coastal Sand Dunes[edit]
Historically, coastal towns of Connecticut have always harbored the majority of Connecticut's O. humifusa colonies. Although coastal areas of Connecticut still possess the greatest concentration of O. humifusa, it is believed that "development of coastal habitats has probably extirpated all but a select few populations in Connecticut."[3] Thus, over the last 150 years, O. humifusa has experienced a widespread decline in population throughout this historic coastal stronghold.
In my research, "coastal colonies" are defined as those colonies living no more than 1000 feet from Long Island Sound (this category also includes those colonies of O. humifusa found on islands off the coast of Connecticut). Any colonies living in Connecticut north of this boundary are considered "inland colonies" for the purposes of my research. Typically, "coastal colonies" are found at elevations not exceeding 40 feet above mean sea level (AMSL), though strictly speaking, elevation is not a determining factor in their categorization as "coastal" and some coastal colonies may occur at higher elevations.
Habitat Requirements[edit]
Substrate Stability[edit]
A study was performed in Canada's Point Pelee National Park in which juvenile O. humifusa cacti were planted on a sandy beach and monitored to determine the suitability of that habitat for use during future restoration projects. This study revealed what may be the most important limiting factor in the viability of sandy, coastal regions as long-term humifusa habitat. It was determined that "sand burial took a toll in terms of survival and plant size" and that O. humifusa "may not tolerate disturbance in mobile sandy substrates".[4] The study later goes on to state that "their numbers declined such that there would be no survivors after 2-3 more years, if the current rate of mortality continued" and that "self-sustaining populations could not be established...since transplants would not live long enough to reach sufficient size to flower and bear fruit." [4]
The results of this study do not indicate that all sandy coastal habitats are unsuitable as O. humifusa habitat. Indeed, the colonies present at Milford and Stratford, Connecticut are evidence to the contrary. Instead, the study helps us to distinguish suitable coastal habitat from unsuitable habitat. We can conclude that the ability of a given sandy coastal area in Connecticut to provide suitable, long-term habitat for O. humifusa cacti is likely to hinge upon the substrate stability of the site. Any factor which could lead to intermittent, partial burial of the cacti by sand, such as frequent flooding or unobstructed wind, would only serve to weaken the plants. In other words, classic sand dunes and other sandy coastal areas which are mostly devoid of plant life and subject to episodic disturbance by wind or water are unsuitable O. humifusa habitat, while stable-substrate, erosion-resistant, sandy coastal scrubland offers suitable habitat.
The O. humifusa colonies observed at Milford (Milford Point Colony) and Stratford, Connecticut (Short Beach Colony) seem to support this claim. For instance, it seems counter-intuitive that O. humifusa would be found interspersed throughout the sand alongside taller trees and shrubs which would undoubtedly serve to reduce the length of time during which full, unobstructed sunlight is available. However, it may well be that these trees and shrubs provide crucial substrate stability both by acting as a windbreak and due to the fact that the accompanying network of roots affords an added measure of erosion resistance.
Substrate Salinity & Salt Spray[edit]
Because coastal colonies of O. humifusa grow upon habitat which may possess exceptionally high levels of dissolved salts (as well as be subject to occasional flooding by saltwater), it is of interest to explore how coastal specimens deal with excess salts. It has been observed that colonies of O. humifusa living in the immediate vicinity of the seashore "accumulated more Na+ in their cladodes and appeared to be better adapted to aerial salt spray as well as episodal high salinity in the root medium than inland individuals".[5] Thus, O. humifusa is accommodating of high-salinity, even developing certain tolerances to high levels of dissolved salts which aren't possessed by cacti of the same species from inland colonies.
Inland Rocky Ridges[edit]
Even as early as the mid-1800s, it was observed by botanists that O. humifusa colonies were very fragmented in their inland distribution. I would estimate, based upon historic records and my own field examinations of extant colonies, that there may be as many as a dozen inland colonies in the state, perhaps less. I have thus far confirmed only five inland colonies in four towns (Hamden, New Haven, Old Saybrook and Plainville), though my research has revealed that at least eight inland towns in Connecticut were historically known to host wild O. humifusa colonies.
Indeed, research reveals that O. humifusa colonies on rocky or sandy inland habitats were once much more common than they are today. In all likelihood, many inland colonies have been lost to the natural process of forest succession whereby areas that were cleared for timber or previously maintained as open pastures are abandoned (generally between 1650 and 1850) and recolonized, first by shrubs and pioneer trees and eventually by thick forest. Since O. humifusa requires full sunlight, a good number of colonies are likely to have perished as the forest regenerated and shaded them out.
In my research, "inland colonies" are defined as those colonies living on the mainland that are more than 1000 feet from Long Island Sound. This category also includes those colonies of O. humifusa that may be found nearby inland riparian habitats. Any colonies living further south than this boundary are considered "coastal colonies" for the purposes of my research. Typically, "inland colonies" are discovered at elevations no less than 100 feet AMSL, though elevation is not a determining factor in their categorization as "inland" colonies and it is possible that inland colonies may be found at lower elevations.
Habitat Requirements[edit]
Soil & Geology[edit]
| Overview of Soil Characteristics of Inland O. humifusa Habitats | |
|---|---|
| Soil Characteristic | Description |
| Soil Type | 80% : Holyoke-Rock Outcrop Complex (Soil Type 78) 20% : Charlton-Chatfield Complex (Soil Type 73) |
| Soil Slope Types | 60% : 3 to 15 percent slope (Soil Type 78C) 40% : 15 to 45 percent slope (Soil Types 78E & 73E) |
| Soil Drainage | 100% : Well-drained |
| Soil/Bedrock Reactivity | 100% : Extremely acidic to moderately acidic |
| Soil Composition | 100% : loam over glacial till deposits |
| Bedrock Composition | 60% : (1) diabase, (2) basalt, (3) gabbro 20% : (1) basalt, (2) gabbro 20% : (1) gneiss, (2) granite, (3) schist |
Approximately 80% of the inland O. humifusa colonies that I have thus far discovered are found upon terrain with a soil type described as Holyoke-Rock Outcrop Complex (Soil Type 78) by the Soil Survey of the State of Connecticut (SSSCT) produced by the United States Department of Agriculture and the Natural Resources Conservation Service. Of that 80%, approximately 75% of those colony areas can further be sub-classified as exhibiting a 3 to 15 percent slope (Soil Type 78C). The West Rock Shephard Colony of Hamden was found on terrain that is classified as having a 15 to 45 percent slope (Soil Type 78E), however the colony location is very close to the transition line between soil types 78C and 78E and is therefore not a significant outlier. Thus, it can be stated that inland Connecticut O. humifusa colonies occur frequently on Holyoke-Rock Outcrop Complex with a slope between 3 and 45 degrees (or a mean slope of approximately 19 degrees).
The SSSCT describes Holyoke-Rock Outcrop Complex (78C and 78E) as "gently sloping to strongly sloping", "bedrock-controlled" hills and ridges "on uplands" where the depth to bedrock does not generally exceed 20 inches. The parent material of these habitat areas includes "loamy eolian deposits over melt-out till derived from basalt and/or sandstone and shale". Of particular interest is the fact that the soil of Holyoke-Rock Outcrop Complex is typically well-drained and "extremely acidic to moderately acidic".[6]
Further analysis using the Connecticut Environmental Conditions Online (CTECO) GIS Map of Critical Habitats revealed that 60% of Connecticut's confirmed inland O. humifusa colonies are found on habitat that is designated as Subacidic Rocky Summit Outcrops (SubRSO). CTECO describes these habitat areas as "dry to xeric exposed summits, ledges and other outcrops", noting the geologic composition to be "primarily basalt and other mafic rocks", where vegetation is typically restricted to "low shrubs, grasses and herbs". [7] While the Metacomet Colony habitat is not identified as Critical Habitat SubRSO, the conditions I observed there are congruent with the habitat description and it is likely this area was incidentally neglected on the CTECO Critical Habitat GIS Map.
Approximately 60% of confirmed inland colonies are found upon West Rock Ridge in New Haven and Hamden, Connecticut on a bedrock type known as West Rock Dolerite (USGS Code Jwr). The Metacomet Colony in Plainville, Connecticut has a bedrock type defined as Holyoke Basalt (USGS Code Jho). However, basalt is the common thread between these two bedrock types, with Holyooke Basalt being comprised primarily of basalt with gabbro as a secondary rock type while West Rock Dolerite is primarily composed of diabase with basalt and gabbro as secondary and tertiary rock types. The reactivity of these bedrock types ranges from subacidic (in the case of Holyoke Basalt) to somewhat pH neutral (in the case of West Rock Dolerite).
All of these observations seem to suggest that O. humifusa is partial to acidic soil which is rich in diabase, basalt and gabbro. However, this conclusion was seriously challenged when I documented the Ingham Hill Colony of O. humifusa in Old Saybrook. The Ingham Hill Colony exists on soil defined as Charlton-Chatfield Complex (73E) (which contains a mix of granite, schist and gneiss) on a bedrock type defined as Monson Gneiss (USGS Code Omo). The discovery of this colony seriously undermined my previous conclusion that inland O. humifusa had a special affinity for traprock ridges and I have since withdrawn my theory that the species exhibited a unanimous preference for basalt.
Instead, it is now my belief that the frequency at which O. humifusa appears on traprock ridges is merely a reflection of the fact that traprock ridges are especially common in Connecticut. In many towns, the only sunny, exposed ledges are found upon these traprock ridges, so that O. humifusa simply has nowhere else to grow. I do not believe that O. humifusa has any special preference for basalt, but that the high rate of occurrence of O. humifusa on basalt ridges is merely incidental.
While O. humifusa may not have any strong preference for soil of a specific composition, there are nonetheless certain characteristics of soil that must be met in order for it to qualify as acceptable habitat for O. humifusa. Every inland colony thus far discovered has been found upon soil that is especially well-drained and which is classified as moderately acidic to extremely acidic. These soil characteristics are found at every O. humifusa colony site, including the unusual Ingham Hill Colony site.
Elevation[edit]
Prior to the discovery of the Ingham Hill Colony at Old Saybrook, there seemed to be sufficient evidence that inland colonies of O. humifusa preferred elevations of between 350 and 550 feet above mean sea level (AMSL). Since the discovery of the Ingham Hill Colony, though, this assertion has been seriosuly challenged and I no longer believe O. humifusa has any particular elevation preference.
With the exception of the Ingham Hill Colony, O. humifusa colonies upon inland ridges certainly present a tight correlation in elevation. The Metacomet Colony is at an elevation of ~399 feet AMSL, the West Rock South Colony is at ~429 feet AMSL and both of the northern West Rock colonies range in elevation from ~515 feet AMSL at their highest to ~425 feet AMSL at their lowest. These elevations are tightly clustered between 350 and 550 feet AMSL, which had hitherto lead me to believe that there was some advantageous quality to this range of elevations which O. humifusa preferred. However, this theory seriously failed to account for those coastal colonies of O. humifusa that are found at significantly lower elevations (rarely exceeding 30 feet AMSL). This fact was especially troubling when trying to determine some meaningful correlation between suitable O. humifusa habitat and elevation.
The discovery of the Ingham Hill Colony in Old Saybrook was particularly important, because the O. humifusa found growing there were at an elevation of roughly 145 feet AMSL. This is the only instance that I have thus far encountered in which O. humifusa could be found at a distinctly intermediate elevation, significantly lower than colonies found on traprock ridges but significantly higher than colonies found in coastal scrubland. Therefore, I have abandoned my previous suspicion that O. humifusa prefers elevations between 350 and 550 feet AMSL. Instead, I would submit that the frequency at which inland O. humifusa occurs at these elevations is simply a product of the terrain of Connecticut, where the rocky cliffs of basalt ridges are very commonly found at elevations between 300 and 600 feet AMSL.
The Ingham Hill Colony proved to be something of a missing link, bridging the previously enormous gap in elevation between coastal colonies and inland colonies.
Indicator Species[edit]
Taking into account all of Connecticut's Opuntia humifusa colonies which I have personally examined, there does not seem to be any single plant community which is especially indicative of the species. That is to say, when we compare flora associated with O. humifusa on coastal sites to the flora associated with the cactus on inland sites, there is very little correlation. It is instructive, then, to examine these two types of habitats separately.
Coastal Indicator Species[edit]
Coastal colonies can be found growing in scrubland with a relatively high diversity of plant life including herbaceous plants, shrubs and trees. All of these associate plants are typically found on warm, dry, sandy habitat along the coast. Thus, I have so far been unable to correlate any specific plant species to O. humifusa on coastal sites.
There is a very minor degree of correlation between coastal O. humifusa and coniferous trees. A field exploration of the Short Beach Colony in Stratford, Connecticut revealed O. humifusa growing amongst an unusually dense concentration of Toxicodendron radicans (Poison Ivy), though I do not have sufficient data at this point in time to believe that this association is anything more than incidental.
Inland Indicator Species[edit]
Inland colonies have demonstrated an undeniable association with Juniperus virginiana var. virginiana, a coniferous juniper known commonly as the Eastern Red Cedar. It would seem that the high-elevation inland habitat requirements for J. virginiana closely mirror those of Opuntia humifusa.
To be clear, it is not as if O. humifusa can be found growing among every high-elevation inland site where J. virginiana thrives. However, the strong association I've observed between these two species leads me to believe that wherever one does happen to find inland O. humifusa colonies, J. virginiana will be found in close association. In fact, when conducting preliminary examinations of satellite imagery prior to an inland field exploration, I oftentimes rule out those potential habitat areas where I cannot see the tell-tale treetops of J. virginiana.
Growth Habits[edit]
There are basically two distinguishable growth habits observed in Connecticut's O. humifusa: "individual plants" and "clonal clusters".
Individual O. humifusa plants are those which exhibit a distinct basal center. While individual plants are almost always smaller than clonal clusters, they tend to grow taller.
Clonal clusters are large patches of O. humifusa which lack a distinct basal center and which are all linked into the same root system. These clusters primarily result from the process of layering, whereby cladodes of a parent O. humifusa plant which contact the ground are able to grow roots of their own, producing a genetically-identical extension of the parent plant. In this way, an individual plant may eventually expand to cover an area between 5 and 30 square feet (or more in some instances).
These two growth habits are, for the most part, readily distinguishable in their most representative instances. However, in some cases, it can be difficult to distinguish whether or not a particular grouping of O. humifusa represents a clonal cluster or simply a series of individual plants growing close to each other.
Highly Variable Morphology[edit]
Opuntia humifusa exhibits a particularly variable phenotype and, for this reason, it has been given several different scientific names across its rather broad range in the Eastern United States and Canada. Over the years, several botanists found specimens of O. humifusa which, in one way or another, differed in appearance so drastically from those with which they were familiar that it seemed quite obvious that the new find must represent a different species. Today, most of these erroneous species have been rejected and are understood to be synonymous with O. humifusa.
Characteristics that can potentially vary from colony to colony, or even between nearby plants in the same colony, include the height of the plants, the prevailing growing habit, the shape of the cladodes, the thickness of the cladodes, the presence of spines or glochids or the lack thereof, the color of spines and glochids and the color the flowers.
Because almost every outward trait of the cactus can vary so significantly in appearance, it is possible to find two plants living in close proximity which appear as if they are indeed entirely different species. Typically, though, plants from two different colonies on two different habitat types (especially a cactus from a coastal colony as compared to a cactus from an inland colony) will exhibit the greatest divergence in appearance from each other. It has been suggested that, due to the fragmented distribution of O. humifusa on isolated swaths of habitat, each disjunct colony may possess unique genetic traits that differ from those found elsewhere.
Response to Insufficient Sunlight Exposure[edit]
While O. humifusa is known to be especially shade-intolerant, colonies can survive under conditions where daily exposure to direct sunlight is somewhat reduced. In these situations, the cladodes (pads) of O. humifusa will tend to grow longer and narrower as a result of a process known as etiolation. Etiolation occurs whenever an O. humifusa plant receives fewer hours of direct exposure to sunlight than preferred. The elongation of the cactus pads is an attempt of the cactus to "reach" towards sunlight, similar to the way in which flower species germinating in the shade will grow long, arching stems in an attempt to reach the sunlight.[8]
Wherever etiolation is observed in O. humifusa, the plant is not receiving an ideal amount of direct sunlight exposure. The Ingham Hill Colony and West Rock North Complex, for example, exhibit particularly long cladodes (shaped like an elongated ellipse) that are undoubtedly undergoing etiolation in an attempt reach toward sunny areas that aren't shaded out by larger trees. In contrast, the O. humifusa of the Long Beach Complex and Short Beach Colony generally have rather short cladodes which are occasionally almost circular in their profile, owing to the fact that they receive plenty of direct sunlight exposure and are not undergoing etiolation, at all.
Although etiolation is a symptom of insufficient habitat conditions, it is not known how long O. humifusa can persist under etiolation conditions. It is possible, though not verified, that a colony may persist for decades under reduced light conditions and possess a nearly permanent etiolated growth habit. However, under reduced-light conditions, O. humifusa has been observed to cease flowering[2], a scenario in which the colony will not be able expand rapidly or disperse beyond its clonal cluster.
Gauging Severity of Etiolation[edit]
Etiolation in O. humifusa results in cladodes that are much longer than they are wide. However, this length-to-width ratio cannot exclusively be used to judge the degree of etiolation of a given specimen. In certain cases, I have discovered specimens growing on warm, exposed sand dunes (receiving no less than 6-8 hours of unobstructed sunlight per day) which exhibit unusually long, skinny cladodes that cannot have occurred due to etiolation, but which must have resulted from some other combination of genetic and/or environmental factors.
Therefore, in determining if a given O. humifusa specimen with elongated cladodes is suffering from insufficient sunlight exposure, it is necessary to consider the conditions of its immediate habitat. Examples of instances in which I have discovered etiolated O. humifusa specimens are as follows:
- Cacti growing within a thick patch of coastal Rosa rugosa (Beach Rose). In this case, the cacti probably colonized the area before the arrival of R. rugosa, which would have quickly overtaken the cacti. In response, the "buried" cacti were growing especially long, rigid cladodes in an effort to hoist themselves towards sunlight. These cacti, which still seemed surprisingly healthy, had already exceeded what is typically thought of as the maximum height of this usually prostrate species.
- Cacti growing upon a tight, rocky glade within the forest. In the case of the Ingham Hill Colony in Old Saybrook, the O. humifusa are being gradually shaded out by encroaching canopy growth. These specimens all exhibit rather elongated cladodes, certainly indicative of etiolation due to the miniminal amount of sunlight exposure available.
In general, elongated cladode length on any given specimen should only be attributed to etiolation in those instances where the affected plant clearly cannot obtain 6 hours of relatively unobstructed sunlight per day.
Reproduction[edit]
O. humifusa can reproduce both vegetatively and by seed. It can also grow by the process of layering, which is not technically reproduction even though it may appear otherwise.
Reproduction by seed begins when an O. humifusa flower, which grows from a cladode, is pollinated. The pollinated flower then develops into a fruit, typically referred to as a "prickly pear", which contains viable seeds. In some cases, these fruits naturally fall off of the parent plant and may germinate on their own. In other cases, the prickly pear fruit is eaten by birds or mammals which cannot digest the seeds. In this way, viable seeds are distributed in the predator's dung, potentially very far from the parent plant. At least one study of O. humifusa found that seeds which passed through the digestive tract of an animal had a higher rate of germination than those that did not.[9]
Vegetative reproduction in O. humifusa occurs when a cladode (or a piece of a cladode) breaks free of a parent plant and takes root. In this way, the broken cladode produces a new plant which is genetically-identical to, but entirely independent of, the parent plant. O. humifusa reproduces rather effectively in this manner.
Clonal clusters of O. humifusa can be produced by a process known as layering, whereby cladodes of an individual plant droop to the ground and begin growing a satellite root system. Layering is an especially common phenomenon observed on rocky inland habitats in Connecticut and a single O. humifusa plant can grow to form a very large clonal mat that covers a dozen square feet or more. However, since layering occurs without the cladode breaking free of the parent plant, the extended root systems produced by layering are actually just extensions of the parent. Thus, layering is technically not a form of reproduction but a form of growth, whereby a single O. humifusa plant expands its size without actually reproducing.
On occasion, it may be difficult to distinguish a cluster of several, individual O. humifusa from a clonal cluster which actually represents a single individual.
Conservation Status[edit]
According to the Connecticut Department of Energy and Environmental Protection, Opuntia humifusa is listed as a species of "Special Concern" in Connecticut. [10] This status is most likely due to the fact that O. humifusa has a naturally restricted range within the state. However, at least one study of O. humifusa has determined that natural succession, whereby previously open swaths of land are colonized by shrubs and shade trees, can result in a corresponding decline in population.[2] I have observed this phenomenon first-hand in Old Saybrook, where the Ingham Hill Colony is in danger of being shaded out as the surrounding deciduous forest grows older and taller. Since very large areas of territory may possess only a handful of O. humifusa colonies, especially in the case of inland habitats, it is entirely possible for forest re-growth to cause local extinction.
Definition of Terms[edit]
While certain terms referring to Opuntia humifusa, such as cladode and glochid, are well-defined and universally agreed-upon, it is necessary to implement some terms which are decidedly less strictly defined or even invented in the course of my own research. These terms include descriptions of the varying growth habits of the cactus, as well as the criteria for evaluating colony structures.
An individual plant is defined as a specimen which strongly exhibits a distinct basal center. Typically, only one to two tightly grouped cladode "stalks" form the foundation of the plant.
A juvenile plant is defined as an individual plant which has less than 6 cladodes and does not yet appear to be able to produce flowers. In many cases, juvenile plants may possess only one cladode which may have grown from seed or from a cladode that broke free of a parent plant. Juvenile plants, however, can also possess a half-dozen small cladodes and be very close to a level of maturation where it may begin to flower. In either case, juvenile plants are always rather small and represent O. humifusa specimens which are undoubtedly young. Due to insufficient study of the species, as well as varying growth rates on different habitat, it is difficult to specify an approximate age range with juvenile plants. Therefore, status as a juvenile is strictly determined by cladode count and the apparent inability of the small specimen to produce flowers and fruits.
Clonal clusters are defined as clumps or mats of O. humifusa which do not exhibit a distinct basal center. These mats can be highly variable in size, ranging from 2 square feet to nearly 40 square feet. From a technical standpoint, the distinction between an individual plant and a clonal cluster can be deceiving, since clonal clusters essentially represent individual plants which simply exhibit a clumpy or mat-like growth habit, thus occasionally becoming very large while still possessing a single, integrated root system.
A colony is defined as an instance in which O. humifusa can be found growing in a specific geographical location. Typically, a colony exists in a small enough area that a single set of coordinates can sufficiently pinpoint the location. Colonies can can range in size from a single, large clonal cluster (West Rock South Colony) to several dozen individuals and/or clonal clusters scattered generously throughout an acre of land.
A complex is defined as series of colonies which, despite being observably distinct, exist in very close proximity to each other. Each distinct colony included a given complex should exist no more than 500 feet from at least one other colony in that complex. Thus, a complex can encompass only a few acres and include only two colonies (West Rock North Complex) or may encompass well over 100 acres and include over a dozen colonies (Long Beach Complex). In certain instances, it is sufficient for two colonies to be grouped into the same complex if there is even little more than one or two individual plants that lie between them at some intermediate point. For example, if Colony A and Colony B are 800 feet from each other, but a lone individual plant can be found growing at some intermediate point in between, then both colonies are considered to be part of the same complex.
I first considered defining something like a complex after discovering two distinct colonies on the northern end of West Rock Ridge in New Haven (formerly West Rock Dunbar Colony and West Rock Shepard Colony) which existed in such close proximity to each other that it might have been possible to mistake them for one continuous colony if one did not examine them at length. The concept became a necessity after I examined the area of Long Beach in Stratford and Bridgeport, where colonies could be found liberally distributed over the course of nearly a mile of peninsular beach and scrubland. In such a case, it would simply be impractical to attempt to affix a unique name to each colony found in such a densely populated area. In these instances, the introduction of the concept of the complex serves to simplify the naming process and identify an area where O. humifusa is more locally widespread than at an isolated colony.
Confirmed Colonies[edit]
Through field exploration, I have confirmed the existence of O. humifusa colonies in the following locations. Where applicable, GPS tracklogs and photographs are supplied.
Metacomet Colony (Plainville)[edit]
The Metacomet Colony is a relatively small colony of Opuntia humifusa that can be found on traprock ridge in Plainville, Connecticut near Pinnacle Hill. The colony derives its name from its close proximity to the Metacomet Trail, which runs within ten feet of the cacti.
Background Information[edit]
The general location of a colony of O. humifusa living in Connecticut was documented in an online article by Stephen Wood (creator of the website Connecticut Museum Quest) on October 6, 2007[11]. Wood reported finding these cacti along the Metacomet Trail in Plainville, Connecticut, however he did not supply a precise location. The article was accompanied by photographic evidence. Further research seems to suggest that this colony was known to at least a few individuals as early as 2005.
Exploration[edit]
April 15, 2012[edit]
On April 15, 2012, I conducted a field exploration along a section of the Metacomet Trail in Plainville that followed the same route taken by Wood during his 2007 hike. Within approximately 1/4-mile of hiking, I discovered a sandy, sun-baked ledge adjacent to the trail upon which there were several O. humifusa. In all likelihood, this colony is the same one that Wood documented five years earlier, owing to the apparent health of these cacti.
During that same field exploration, I carefully explored several other ledges (over the course of approximately 1.25 miles) which seemed to present a habitat similar to that of the ledge with the confirmed cactus colony. I was unable to document any further colonies of O. humifusa along the Metacomet Trail.
Status[edit]
My field exploration has identified a single ledge along the Plainville-section of the Metacomet Trail upon which a colony of O. humifusa currently lives. This colony is known to have existed for at least five years and seemed, upon examination, to be relatively healthy. Although many ledges with a similar habitat can be found along nearby stretches of the Metacomet Trail, my explorations have led me to conclude that there are no further colonies in the area.
Concerns About Preservation[edit]
The colony of O. humifusa identified along the Metacomet Trail is apparently healthy, but it is relatively small and confined to a single ledge that is easily accessible. Thus, the colony (and the very existence of O. humifusa in the area) is potentially subject to severe impact by natural or human disturbance such as wildfires, extreme weather conditions, incidental tree fall, foot traffic by hikers and unlawful specimen collection. Any one of these factors, or any combination of them, could weaken, deplete or destroy the cactus colony.
Colony Location and Statistics[edit]
The Metacomet Colony is located in Plainville, Connecticut at 41.672165° , -72.831497°.
- To view this location in Google Maps, click here.
- To download the GPS tracklog of this exploration (KML format), click here.
Pertinent statistics concerning the location include:
- Elevation of Colony: ~399 feet above sea level
- Surficial Geology: Basalt
- Habitat Type: Inland Cliffs/Mountain Peaks [12]
Milford Point Colony (Milford)[edit]
The Milford Point Colony is a large colony of Opuntia humifusa living within the Smith-Hubbell Wildlife Refuge, an 8-acre parcel of preserve land adjacent to the Audubon Coastal Center at Milford Point. The colony derives its name from the Audubon sanctuary (which, in turn, derives its name from a common term for the peninsula in Milford, Connecticut).
Background[edit]
On a website dedicated primarily to gardening with native plant species, an article about Opuntia humifusa briefly mentions that the cactus "grows naturally in Connecticut along the coast. You can see it at the Milford Point Coastal Audubon Center along the boardwalk."[13] Known formally as the Coastal Center at Milford Point, the preserve is owned and managed by the Connecticut Audubon Society and is comprised of an 8.4-acre protected barrier beach in Milford, Connecticut.[14]
Exploration[edit]
April 28, 2012[edit]
On April 28, 2012, I conducted a field exploration of the Audubon Coastal Center at Milford Point during which I explored the relatively small nature preserve for Opuntia humifusa which, based upon my previous research, were likely to found along the beach boardwalk. This exploration involved a very short walk from the parking area to the boardwalk, as well as a brief off-trail survey of the area in which the cacti were discovered. In total, my route covered approximately 0.29 miles.
Congruent with the claims discovered during my research, O. humifusa were visible from the short boardwalk which traverses a series of dunes and terminates at the seashore. In many cases, these plants were only one to two feet from the boardwalk, unobstructed by any railings.
Although the boardwalk offered access to a few cacti, it was clear that other cacti could be found deeper in the dunes which were obstructed from view by various trees and shrubs. In order to obtain a rough estimate of the total number of cacti on the property, I left the boardwalk and conducted a survey of all those portions of preserve which could reasonably be accessed by foot. In total, I was able count 19 individual O. humifusa spread out over an area of approximately 1/2 acre. Since my investigation of the dunes was not exhaustive, it is fair to say that my count is strictly a conservative estimate of the total cacti growing at Milford Point.
Status and Description[edit]
My field exploration of the Audubon Coastal Center at Milford Point has revealed that Opuntia humifusa are a "featured" attraction at this preserve. The colony of cacti is not only exceptionally easy to find, but the boardwalk that traverses the dune area seems to have been constructed, in part, with the specific intention of exposing preserve visitors to wild cacti.
The colony of O. humifusa on Milford Point covers approximately 1/2-acre and includes at least 19 plants, however the actual number of plants is likely to be at least 10% higher than this estimate. Most of these cacti were "individuals", which is to say that there were very few which had formed large clonal clusters.
These findings stand in stark contrast to those of the colonies that I have discovered on inland ridges, which are generally isolated to a very small area (less than 50 square feet) and tend to be centered upon a clonal cluster, with "individual" plants accounting for less than half of the bio-mass of each colony.
The cacti colony at Milford Point was interspersed amongst dune shrubs, short coniferous trees and a variety of herbaceous plants. In some cases, O. humifusa were found growing around the bases of trees and shrubs, while in other instances they were growing upon clearings in the dune with a certain margin of open sand between other plant life. This, again, stands in stark contrast to inland mountain sites, upon which O. humifusa grows in areas with an exceptionally low diversity of trees and plants.
Concerns About Preservation[edit]
Of all of the sites at which I have observed Opuntia humifusa, the Coastal Center at Milford Point offers the easiest access to these plants while at the same time providing the greatest level of protection.
While the cacti colonies in Plainville and New Haven are found upon state-owned property such as West Rock Ridge State Park and the Metacomet Trail, these parcels of land are very large and protective legislation is nearly impossible to routinely enforce.
The Audubon Coastal Center at Milford Point, while providing similar protective regulations, encompasses a very smaller parcel of land (less than 9 acres) upon which it is considerably more practical to conduct regular assessments of the colonies health. Thus, I am confident that the colony of O. humifusa at Milford are relatively safe under the protection and monitoring of Audubon Center staff.
Colony Location and Statistics[edit]
The Milford Point Colony is located in Milford, Connecticut at the Audubon Coastal Center at Milford Point. The coordinates of the colony within the Audubon Center are 41.175451° , -73.100733°.
- To view this location in Google Maps, click here.
- To download the GPS tracklog of this exploration (KML format), click here.
Pertinent statistics concerning the location include:
- Elevation of Colony: ~14 feet above sea level
- Surficial Geology: Sand (composed primarily of quartz)
- Habitat Type: Coastal Sand Dunes [12]
West Rock Colonies (New Haven & Hamden)[edit]
There are three colonies of Opuntia humifusa found within the boundaries of West Rock Ridge State Park, which extends south to New Haven and north to Hamden. The West Rock South Colony is located in the southern half of the park within New Haven. The West Rock North Complex is comprised of two colonies which are located in the far-northern end of the state park.
Geographic & Historic Overview[edit]
West Rock Ridge is a prominent traprock ridge in Connecticut that runs in a north-south direction, extending roughly 5 miles from Hamden to northern New Haven and skirting the borders of Woodbridge and Bethany along its western edges. Although West Rock Ridge is now almost entirely contained within the 1,800-acre West Rock Ridge State Park, this was not always the case. West Rock Ridge, as a protected parcel of land, began in 1826 as a small 50-acre city park in New Haven (along the southern end of the ridge). By 1975, the State of Connecticut had established West Rock Ridge State Park on areas of the ridge which were not owned by New Haven. By 1982, New Haven's city park on West Rock Ridge had grown to encompass roughly 600 acres of land, all of which was donated to the state that year to be incorporated into West Rock Ridge State Park. Further parcels of land were added to the state park whenever they became available, swelling the park grounds to the roughly 1,800 acres that it encompasses today.[15]
Background Information[edit]
Although plenty of records exist which suggest the presence of Opuntia humifusa on West Rock Ridge, very few of these records offer any specific information as to where the cactus can actually be discovered. This was of particular concern because West Rock Ridge State Park is over 5 miles long, extending from New Haven in the south to Hamden in the north (and even straddling the borders of Woodbridge and Bethany on its western edges). Launching precisely targeted explorations of West Rock Ridge required the extensive study of satellite imagery, which permitted me to focus upon those areas which are not heavily forested and, thus, have at least some measure of potential to be O. humifusa habitat.
The oldest evidence that I've thus far discovered which attests to the existence of Opuntia humifusa in New Haven, Connecticut dates to the mid-1800s. A Report on the Trees and Shrubs Growing Naturally in the Forests of Massachusetts, Volume 2, published in 1846, very briefly mentions that the O. humifusa "is said to be found at New Haven, in Connecticut."[16] No specific information is provided concerning the whereabouts of a colony.
In a modern written overview of West Rock Ridge in New Haven, Connecticut, the West Rock Ridge Park Association notes that the ridge offers an "extraordinary biodiversity of plants and animals from prickly pear cactuses to 230 species of birds".[17] The text does not offer any further mention of O. humifusa, nor does it offer photographic evidence.
Further supporting this claim, an article was published on the website of the Mycological Society of America which details a group hike throughout West Rock Ridge scheduled to take place in 2012 during the organization's annual meeting. Although the organisms of interest to mycologists are primarily mushrooms and other fungi, the article nonetheless states that hikers in the West Rock Ridge area "occasionally [find] prickly pear cactus".[18] No further mention of cacti is made in this article.
The compelling evidence of the presence of O. humifusa on West Rock Ridge comes in the form of a photograph taken by Michael Hornak in 2011. The image portrays O. humifusa in bloom and the geo-tag data pinpoints the location of the plant to be at the far northern end of West Rock Ridge State Park in Hamden, Connecticut.[19]
Exploration[edit]
A preliminary examination of satellite imagery of West Rock Ridge revealed several areas along the southern end of the park where habitat suitable for O. humifusa potentially existed. Because the southern end of the ridge has a greater concentration of areas that aren't covered with thick forest, my earliest exploration focused on this region. Exploration of the northern end of the ridge was conducted later after the discovery of Hornak's O. humifusa photograph.
April 28, 2012[edit]
I conducted a field exploration of the southern half of West Rock Ridge State Park on April 28, 2012, during which I carefully investigated all of the target areas in that region that were identified in my preliminary studies of satellite imagery. This entailed a hike of approximately 3.08 miles and the route variously included hiking on foot trails and along the park road. Extensive bush-whacking was required in order to explore all of the target locations, many of which were between 20 and 100 feet off of the road or established trails.
Target areas of exploration primarily included west-facing and south-facing ledges along the precipices of the southern half of West Rock Ridge. Most of these areas were devoid of trees or, at least, very sparsely forested. A thorough investigation of these target areas revealed no presence of Opuntia humifusa.
However, I did succeed in locating a healthy colony of cacti in an area which was not within my original list of target areas. The colony was located on a relatively small clearing within the forest towards the interior of the ridge. This clearing consisted of an isolated, slightly elevated dome of exposed bedrock which enjoyed full sunlight and supported a bare minimum of herbaceous plants. The colony included one large clonal cluster of cacti as well as a number of individual cacti along the outer perimeter of the clearing which were at various stages of maturation.
May 5, 2012[edit]
A second field exploration was conducted on May 5, 2012 and involved an investigation of approximately 1.09 miles on the far northern extent of West Rock Ridge in Hamden, Connecticut. This exploration revealed several areas, some quite large, where bedrock was exposed at the surface and there was a bare minimum of tree growth. However, most of these "obvious" areas yielded no findings. Eventually, I ventured to the steep, terraced precipices on the eastern side of the ridge and succeeded in discovering a large clonal colony of O. humifusa. I quickly noticed that this uppermost cluster was only the tip of the iceberg, as further clonal clusters could be seen growing on several lower ledges descending the face of the ridge.
After thoroughly documenting this colony, I began moving northwards and checking similar habitat for the presence of another colony. I succeeded in discovering another colony approximately 200 feet further north of the first. This colony shared a similar character with the nearby find, where a several clonal clusters could be found on successively lower-elevation ledges.
Status and Description[edit]
West Rock South Colony[edit]
My first field exploration identified a small, isolated, exposed patch of bedrock within the forest on the southern half of West Rock Ridge in New Haven, Connecticut upon which a colony of Opuntia humifusa currently lives. I have not found any explicit evidence that the location of this colony has been previously documented.
The colony, which I have named West Rock South Colony, consists of a large, clonal patch covering approximately 25 to 35 square feet. Within 5 to 10 feet of this clonal center were approximately 6 or 7 individual outlying "satellite" cacti.
There is a bare minimum of herbaceous plants on the cacti habitat, as would be expected. The most prominent additive feature of this colony is a large, gnarled, many-trunked juniper, specifically an Eastern Red Cedar (Juniperus virginiana var. virginiana). The large clonal mass of cacti can be found tightly skirting the base of this tree.
West Rock North Complex[edit]
My second field exploration identified two very large colonies of Opuntia humifusa on the east-facing cliffs at the far northern end of West Rock Ridge in Hamden, Connecticut. These colonies are situated barely 200 feet from each other and are rather significant inland colonies in Connecticut, primarily for their striking demonstration of circumstances in which O. humifusa can effectively expand its range via barochory (gravity) as opposed to zoochory (animal-assisted seed dispersal). Although these two colonies were originally given separate names (West Rock Shepard Colony and West Rock Dunbar Colony), they were later collectively renamed the West Rock North Complex after changes to my naming conventions enacted in July 2012.
Both of these colonies exhibit a structure which is supremely demonstrative of a scenario in which O. humifusa can successfully colonize surrounding habitat. The uppermost clonal clusters of each colony are found at an elevation of roughly 500 feet. Interestingly, numerous further clonal clusters can be found immediately below on successive terraced ledges that extend as far as 50 to 100 feet down the face of the ridge. My observations suggest that the clonal clusters at the highest elevations are most likely the oldest, progenitor clusters and that, as cladodes and fruits broke free of these older plants, they would tumble down the face of the ridge. Whenever these disconnected cladodes or fruits came to rest on a lower ledge, they would take root or germinate and produce a new clonal cluster. Over a number of years then, these colonies became quite large and can be described as "cascading" down the face of the ridge.
I counted at least a dozen clonal clusters and as many as two dozen individual cacti in the southernmost of the two colonies. The northernmost has fewer individual plants but its clonal clusters, of which I counted roughly ten, tended to be larger. But the most impressive characteristic of this complex is the role which gravity has played in expanding the size of the colonies over time. Both of these colonies probably began as a single, high-elevation clonal cluster on the uppermost ledges of West Rock Ridge. With the help of gravity to carry broken cladodes and fruits to lower-elevation ridges, a process known as barochory, those two original colonies each expanded their mass by at least 1000%. Indeed, the West Rock North Complex offers a rare demonstration of just how remarkably effective O. humifusa can be in expanding its local range without the assistance of animals as intermediaries, at least so long as the terrain is such that gravity can be harnessed to widely distribute fruits and broken cladodes. No where else in Connecticut have I discovered a colony which clearly demonstrates the enormous potential of O. humifusa to harness barochory.
The West Rock North Complex was found in close association with Eastern Red Cedar (Juniperus virginiana var. virginiana) just as the considerably smaller West Rock South Colony.
Concerns About Preservation[edit]
The West Rock South Colony of Opuntia humifusa (identified on the southern half of West Rock Ridge) is apparently healthy but, as is typical of inland colonies, it is relatively small and confined to a single rocky outcrop. Despite the fact that this colony is only about 60 feet off of the southern park road, it is unlikely that this colony is at risk of easy discovery. There aren't any parking areas within close range to the colony, meaning that park traffic is not likely stop in the immediate vicinity. In addition, there are no trails that lead to the rocky clearing, so hikers aren't likely to happen the colony. Thus, there is a bare minimum of concern about the preservation of the O. humifusa colony at this site and a high probability that it will persist well into the future.
The colonies of the West Rock North Complex (identified on the northern end of West Rock Ridge) are exceptionally healthy and quite large. Although hiking trails run within 40 or 50 feet of the clonal clusters at the highest elevations, the cacti would be difficult to spot unless one were expressly looking for them. Furthermore, the "cascading" quality of these colonies means that, even if harm were to come to the more accessible high-elevation clonal clusters, those clusters on the lower ledges would still flourish by virtue of their relative inaccessibility. There is little concern about the preservation of this O. humifusa complex.
Colony Locations and Statistics[edit]
West Rock South Colony[edit]
The West Rock South Colony is located in New Haven, Connecticut at West Rock Ridge State Park. The coordinates of the colony within the park are 41.335736° , -72.964300°.
- To view this location in Google Maps, click here.
- To download the GPS tracklog of this exploration (KML format), click here.
Pertinent statistics concerning the location include:
- Elevation of Colony: ~429 feet above sea level
- Surficial Geology: Unknown (likely Basalt)
- Habitat Type: Inland Cliffs/Mountain Peaks [12]
West Rock North Complex[edit]
The West Rock North Complex, comprised of two distinct colonies, is located in Hamden, Connecticut at West Rock Ridge State Park. The coordinates of the southernmost colony are 41.398765° , -72.945621°, while the coordinates of the northernmost colony are 41.398970°, -72.944514°.
- To view the location of the southernmost colony in Google Maps, click here.
- To view the location of the northernmost colony in Google Maps, click here.
Pertinent statistics concerning the location of the complex include:
- Elevation of Colony: Ranges from ~508 feet to ~430 feet above sea level
- Surficial Geology: Basalt
- Habitat Type: Inland Cliffs/Mountain Peaks [12]
Short Beach Colony (Stratford)[edit]
The Short Beach Colony is a large colony of Opuntia humifusa spread generously throughout about one to two acres of flat, sandy scrubland fronting Long Island Sound at Short Beach Park in Stratford, Connecticut. The colony is named after the beach park in which it was found.
Background[edit]
Unlike all of my other finds (as of May 2012), I had no prior research indicating the existence of Opuntia humifusa within Stratford's Short Beach Park. While my research did reveal that O. humifusa was known to live in Stratford, Short Beach Park was not among the known locations that I was able to dig up. Thus, when I decided to investigate this area, it was purely on a whim. I simply knew that O. humifusa was documented as living nearby (within only a mile or so along similar beachfront land), so I thought that I might investigate.
Exploration[edit]
May 9, 2012[edit]
On May 9, 2012, I conducted a field exploration of Short Beach Park in which I focused exclusively upon a swath of sandy scrubland found within. This exploration involved roughly 1/2-mile of walking in total, during which I attempted investigate all of the potential habitat areas in the immediate vicinity.
Although I uncovered no material in my research which suggested the presence of Opuntia humifusa at Short Beach Park, I was surprised to discover the first specimen within only a minute or two of searching. Subsequently, I discovered numerous other specimens spread out over roughly an acre.
These cacti are actually rather easy to find, which may seem odd considering that no literature, articles or photographs of them can be found online. There are probably three factors which contribute to this lack of publicity. First, Short Beach Park is generally open only to residents of Stratford, meaning that the park doesn't get nearly as many visitors as if it were open to surrounding towns. Second, those Stratford residents that do visit the park probably tend to be interested primarily in visiting the sand beaches, not the scrubland behind them. Finally, one of the most common herbaceous plants that I found in association with this colony was Toxicodendron radicans (Poison Ivy), a highly-allergenic plant which is readily identifiable and generally avoided at all costs by humans. Some combination of these three factors is responsible for the relative "secrecy" of this colony despite the fact that it is easily accessible and found in extremely close proximity to heavily-visited beachfront.
Nonetheless, there is a trail matrix weaving throughout the scrubland which I doubt is of natural origin, so there must be some measure of human tending/landscaping to the area, as well as at least some regular foot traffic. Thus, this colony is probably well-known locally, but simply hasn't been publicized for one reason or another.
Status and Description[edit]
My field exploration of Stratford's Short Beach Park has revealed a large colony of Opuntia humifusa growing on dry, sandy scrubland behind the sand beach. Despite being little-known throughout the state, this colony is probably rather well-known to those Stratford residents that frequent the park since it is easily accessed from high-traffic beach areas.
The Short Beach Colony contains specimens that are spread throughout an acre (or more) of land, with most specimens being at least 15 to 20 feet apart. I counted a total of 14 O. humifusa specimens: four (4) large specimens, five (5) small specimens and five (5) specimens of intermediate size. Although there is always some measure of inaccuracy with these counts, owing to the clonal growth habits of O. humifusa, this count is rather thorough.
Interestingly, there did not seem to be any significant clonal clusters at all, a finding which is congruent with the Milford Point Colony and which contrasts sharply with colony structures found on inland ridges. Although I did count four "large" O. humifusa specimens at Short Beach, these were relatively tall plants which, unlike clonal colonies that I've observed, still maintained a tight, individual structure with a discernible basal center.
The habitat area at Short Beach is exceptionally similar to the habitat area at Milford Point. At both of these habitat areas, the O. humifusa specimens are interspersed amongst dune shrubs and low-growing herbaceous plants along with a few coniferous trees, though the Short Beach habitat exhibited a lower density of coniferous trees and higher density of shrubs than the Milford Point habitat. Also congruent with Milford Point, O. humifusa did not seem to have a preference for any particular margin from larger shrubs; some specimens were found growing right at the base of shrubs, while others were found in more open, exposed areas amongst sparse, low-growing herbaceous plants.
The Short Beach Colony exhibited a similarly high diversity of associated plant life as the Milford Point Colony. At least one of those herbaceous associates was Toxicodendron radicans (Poison Ivy), which was exceptionally prevalent. However, because T. radicans can be found in a wide range of habitats where there are no cacti, it cannot yet be considered anything more than an incidental associate (that is, I do not yet consider T. radicans to be a useful indicator species).
Possibility of Human Introduction[edit]
Research into the history of Short Beach Park reveals that, as late as the early 1970s, there were numerous cottages there and the northeastern section of the park was being used as a town dump of sorts.[20] The last of the cottages were demolished in 1972 after the town emerged as the victor of a 15-year debate over whether the cottagers or the town held ownership over the land. At some point afterwards, between 1972 and 1973, Short Beach was developed as a town park.
Given these findings, there is some measure of question as to whether or not the O. humifusa that can be seen today at Short Beach were introduced by the park designers. On one hand, these cacti are on ideal habitat and would seem to be natural in origin. On the other hand, it is entirely possible that this habitat area did not exist prior to park development.
At this point, I do not possess enough information to make any conclusions in this regard.
Concerns About Preservation[edit]
Although the Short Beach Colony is easily accessible and in close proximity to areas that likely receive a good deal of foot traffic, I have minimal concerns about preservation. The plants are relatively inconspicuous unless you are looking for them and they seem to have fared very well thus far. I cannot think of any reason why this would change in the foreseeable future.
Colony Location and Statistics[edit]
The Short Beach Colony is located in Stratford, Connecticut at Short Beach Park. The colony is spread out over a large area (approximately one acre), so it is not possible to provide pinpoint coordinates that are sufficiently representative. Suffice to say, the westernmost O. humifusa specimen is located at 41.1638° , -73.1093°, while the easternmost specimen is located at 41.1648°, -73.1090°.
- To view the westernmost location in Google Maps, click here.
- No GPS track log was recorded for this exploration.
Pertinent statistics concerning the colony location include:
- Elevation of Colony: ~5 feet above sea level
- Surficial Geology: Sand (composed primarily of quartz)
- Habitat Type: Coastal Sand Dunes [12]
Ingham Hill Colony (Old Saybrook)[edit]
A single colony of Opuntia humifusa can be found on a rocky forest glade beside a powerline cut in northern Old Saybrook, Connecticut. There is no formal parking area for the powerline cut, but it can be accessed on foot through a row of trees on the western side of Essex Road (Rt 153) in Westbrook, Connecticut. To be clear, the O. humifusa colony is not on the powerline cut. Rather, it is roughly 200 feet south of the powerline cut in the nearby forest. The colony is named after a series of three, non-connected roads in the vicinity of the colony which are all peculiarly named Ingham Hill Road.
Background Information[edit]
The first document I discovered attesting to the existence of an Opuntia humifusa in Old Saybrook came in the form of a newspaper article published in the Shoreline Times on December 28, 2010. The article discussed an on-going controversy over the development of a golf course and residential homes within a coastal forest of nearly 1,000 acres (the only unbroken forest of that size left along Connecticut's coast), describing a recent walkthrough of the proposed areas of development. During the walkthrough, a "large patch of prickly pear cactus, indigenous to the area and listed as a plant of Special Concern...was found on the Westbrook site".[21]
Because the Shoreline Times article did not provide very specific location information, more research was in order. Initially, I was only able to turn up the minutes of an Old Saybrook Planning Commission meeting (January 5, 2011) which, despite referencing the presence of O. humifusa somewhere in the planned development area, still failed to provide specific location information.[22]
Research for this site continued sporadically over the course of three weeks, with other documents surfacing that made mention of O. humifusa without citing a specific location.
Finally, I discovered the website of the Alliance for Sound Area Planning (ASAP), an organization dedicated to the protection of the aforementioned 1,000-acre forest. As part of its mission to educate concerned citizens about the development project, ASAP offers a full compilation of all of the documentation related to the proposed development in Old Saybrook. Within the site plans for the development, the location of the O. humifusa colony is marked for the purpose of ensuring that the species is responsibly addressed during the proposed construction.[23] According to the map, the colony could be found about 0.5 miles west of Essex Road (Rt 153) within approximately 200 to 300 feet from a powerline cut in the forest.
Exploration[edit]
Although the ASAP-hosted map of the Old Saybrook development area does pinpoint the location of O. humifusa, the map itself is somewhat difficult to interpret due to the inclusion of planned roads that do not currently exist. Thus, an examination of satellite imagery was conducted to identify all of the rocky glades in the vicinity which could potentially serve as O. humifusa habitat. I found approximately five (5) glades that were worth exploring.
May 27, 2012[edit]
On May 27, 2012, I conducted a field exploration (~1.5-mile loop hike) of rocky forest in northern Old Saybrook. The forest was accessed on foot from Essex Road (Route 153) in Westbrook, Connecticut via a powerline cut. This exploration focused upon five (5) rocky glades within the forest, each within close range of the mapped colony of O. humifusa identified on proposed development plans for the area.
I succeeded in finding a colony of O. humifusa upon one of the five rocky glades previously identified. Surprisingly, other rocky glades which I had identified, and which offered similar habitat, yielded no further evidence of the presence of O. humifusa.
Status and Description[edit]
My field exploration in Old Saybrook revealed a single colony of O. humifusa living upon a rocky bald within a thick forest. Named the Ingham Hill Colony, it is comprised of what appears to be a single, large clonal cluster of approximately 20 to 30 square feet.
Associated herbaceous vegetation was restricted to sparse grasses and perhaps other inconspicuous low-growing plants. As with all inland O. humifusa colonies discovered (as of May 28, 2012), Juniperus virginiana (Eastern Red Cedar) was a close associate. The colony was essentially growing upon a rocky bald surrounded by a ring of J. virginiana.
In quite a few ways, the Ingham Hill Colony is of special importance to further understanding Connecticut's fragmented population of O. humifusa. The colony can be found growing at an elevation of approximately 140 to 150 feet AMSL. Previously, every colony I had documented was found either on coastal scrubland at an elevation between 5 and 15 feet AMSL, or upon rocky ridges at an elevation of between 330 and 550 feet AMSL. To date, the Ingham Hill Colony is the only colony I have observed at this intermediary elevation. This proves that my earlier deduction, that inland O. humifusa favors elevations from 350 to 550 feet AMSL, is not necessarily true.
In addition, the composition of the soil upon which the Ingham Hill Colony is growing is also quite exceptional in juxtaposition to all other previously-documented inland colonies of O. humifusa. According to the Soil Survey of the Connecticut, the Ingham Hill Colony is growing upon Charlton-Chatfield Complex (Soil Type 73) which is sub-classified as "15 to 45 percent slopes, very rocky" (Soil Type 73E). This soil type, which is derived variously from granite, schist and gneiss, is a notable diversion from the Holyoke soils (Soil Type 78) upon which all other inland colonies of O. humifusa have been discovered, indicating that the cactus is not likely to have any particular affinity for soil derived from basalt, diabase and gabbro, as previously believed. However, this soil type does coincide with other habitat requirements of O. humifusa, being well-drained and "very strongly acid to moderately acid".
Concerns About Preservation[edit]
On one hand, the Ingham Hill Colony is guaranteed protection from potentially invasive development because its presence has been thoroughly documented during site surveys for a proposed golf course. This means that if any future development plans should come to pass, the Ingham Hill Colony will be responsibly handled and appropriated protected.
Unfortunately, the more serious problem faced by the O. humifusa of the Ingham Hill Colony is that of forest succession. Tall deciduous trees tightly crowd the perimeter of the rocky outcrop upon which the colony is growing. Assuming that these trees will continue to grow taller and fuller, extending branches into the gap in the canopy, they will inevitably shade out the O. humifusa, first rendering them incapable of flowering and eventually robbing them of sunlight altogether. This chain of events, should it occur, will serve to eliminate the Ingham Hill Colony in perhaps as little as 10 years.
Judging by the plentitude of stone walls on the forest floor, it is safe to say that the entire area of the modern forest was in use as pasture land until at least the late 1800s. The colony of O. humifusa likely appeared within a decade or two after the pasture was abandoned. At that time, the only trees in the immediate vicinity of the colony would have been the coniferous Juniperus virginiana (Eastern Red Cedar), known to be a hardy pioneer species. Because J. virginiana is relatively low-growing on rocky soils, these trees would have posed no serious threat to the sunlight requirements of O. humifusa. Aerial photography from 1934 shows that the area of the modern-day forest was, at that time, still a patchy scrubland which would've been quite conducive to O. humifusa. The vegetation of this scrubland habitat would've continued to thicken after the 1930s, though. In time, probably between the late 1940s and early 1960s, taller deciduous trees began to dominate the land. Currently, even the ring of J. virginiana surrounding the colony is being shaded out by the deciduous canopy which is nearly twice as tall and growing more dense each year.
Based upon my examination of many O. humifusa colonies in the state, and considering the decidedly shade-intolerant habit of O. humifusa, it is my belief that the Ingham Hill Colony is doomed to be shaded-out within the coming decade. To the best of my knowledge, the loss of the Ingham Hill Colony would represent the extirpation of O. humifusa in Old Saybrook. However, the plight of the Ingham Hill Colony also provides crucial insight into the severe decline of O. humifusa throughout the state since the early 1900s. In all likelihood, extinct colonies that were once known to live inland in towns such as Scotland and Burlington probably suffered the same fate as what seems to lie ahead of the Ingham Hill Colony. That is, those colonies initially grew upon old, rocky fields and pastures which initially provided excellent habitat for O. humifusa. In time, as succession took place turning pasture into meadow and meadow into forest, the O. humifusa would inevitably have been shaded-out and disappeared from the landscape altogether. For instance, tt is possible that the O. humifusa of the Ingham Hill Colony are the last remaining descendants from a colony which was once much larger and more wide-spread throughout the vicinity in past decades.
Colony Locations and Statistics[edit]
The Ingham Hill Colony is located in the northwestern section of Old Saybrook, Connecticut. The coordinates of the colony within the forest are 41.3072° , -72.4165°.
- To view this location in Google Maps, click here.
Pertinent statistics concerning the location include:
- Elevation of Colony: ~145 feet above sea level
- Soil Type: Charlton-Chatfield Complex, 15 to 45 degree slopes, very rocky (Soil Type 73E)
- Bedrock Geology: Monson Gneiss (Omo)
Westwoods Colony (Guilford)[edit]
Initial attempts at locating this colony of Opuntia humifusa proved both frustrating and futile, with roughly 3 miles of hiking throughout the terrain revealing no presence of the plant despite plenty of seemingly excellent habitat. However, armed with the foreknowledge that a colony was found there as late as 2010, I conducted a second exploration of Westwoods nearly two months later and was successful in documenting the largest inland colony of O. humifusa in the state.
Background Information[edit]
In a blog article on A Walk Across the Giant, the author related a story of his hike throughout West Woods in Guilford, Connecticut, noting that his hiking party came upon a large colony of Opuntia humifusa on a ledge beside power lines[24]. This article was published in September 2010 and includes photographic evidence of the find.
Preliminary Assessment[edit]
Initial examination of satellite imagery of Westwoods revealed no shortage of rocky terrain with minimal growth of shade trees. Many of these rocky balds, however, were clearly within a powerline cut that slices through the northern half of the woodlands. Because these power lines are most likely relatively recent in origin, it was unlikely that the cactus colony would be found there.
However, the rocky terrain revealed by the powerline cut was also evident in occasional patches of exposed, rocky outcrops that can be seen within the forest using satellite imagery. These areas offered the ideal habitat for O. humifusa.
Exploration[edit]
On April 28, 2012, I conducted an extensive investigation of a good deal of the potential cactus habitat in the eastern end of Westwoods. Over the course of a 3.1-mile exploration, I came upon numerous locations which seemed to present very promising habitat. Surprisingly, however, I was unable to locate any trace of O. humifusa.
On June 27, 2012, I conducted a second exploration of Westwoods, this time focusing only upon those rocky balds that I had not previously explored two months earlier. This time I was successful in locating a sizable cactus colony, which was to be found upon a long, narrow rocky bald just north of the powerline cut.
Status[edit]
My second field exploration at Westwoods revealed a very large colony of O. humifusa living upon a long, narrow rocky bald that sits atop an otherwise forested hill. I have named these cacti the Westwoods Colony in acknowledgement of fine efforts of preservation and trailblazing that have produced the Westwoods Trails.
The Westwoods Colony habitat is a long, narrow, exposed bald of solid rock, running on a roughly east-west axis, on top of a hill in the northern portion of Westwoods. The colony itself is rather linear in its distribution, forming a thick, patchy row of plants that spans roughly 320 feet along the outcrop. Walking the entire area, I was able to count roughly 25 distinct or semi-distinct clonal clusters ranging from small clusters of only a few square feet to larger clusters upwards of 20 square feet. In addition, countless individual "satellite" plants could found scattered around the clonal clusters, some even growing with little more than 1/4" of dried lichen as substrate. The bio-mass of cacti in this colony is impressive, to say the least, especially considering that the rocky outcrop is nearly devoid of trees such that one that can fully survey the extent of these plants from a single vantage point at the highest elevation of the ledge.
The exposed ledge was tightly bordered by dense broadleaf forest, but the ledge itself was rather bare. The only associated tree life living directly upon the cacti habitat consisted of three or four Juniperus virginiana (Eastern Red Cedar). The presence of these trees further cements J. virginiana as the most significant indicator species of inland O. humifusa, being found at every inland colony/complex location thus far documented.
Perhaps the most unique characteristic of the Westwoods Colony is the degree to which it has claimed such a large portion of habitat on the rocky ledge where it is found. Most inland colonies of O. humifusa are subject to very restrictive swaths of habitat, such as a tiny forest glade or a small rocky outcrop, where the plant has limited opportunities for expanding its claim. Westwoods Colony, on the other hand, is situated upon a rather large rocky bald and it is interesting to observe that O. humifusa has taken advantage of nearly every square foot of suitable terrain available. This aggressive expansion demonstrates just how effectively an O. humifusa colony can expand provided that has ample space on conducive habitat.
Also of note is the elevation at which the Westwoods Colony can be found. The Westwoods Colony is one of the few colonies that can be found at an intermediate elevation, significantly higher than coastal colonies and significantly lower than colonies growing upon ridge tops further inland. The Ingham Hill Colony in Old Saybrook, the first colony to be discovered at such a mid-level elevation and the only other of this type besides the Westwoods Colony, possesses a similar elevation in the range of ~140 feet AMSL.
The composition of the soil upon which the Westwoods Colony is growing is congruent with most inland colonies, being primarily a rocky outcrop of basalt and other typical associated minerals. According to the Soil Survey of the Connecticut, the Westwoods Colony is growing upon Rock Outcrop-Holyoke Complex (Soil Type 79) which is sub-classified as "3 to 45 percent slopes" (Soil Type 79E). This soil type is listed as primarily consisting of bare, surficial rock outcrops (which is consistent with my observations), with soils derived from Holyoke basalt providing the bulk of the loose substrate. The colony area is tightly framed by areas designated as Soil Type 78C to the east and Soil Type 78E to the west, both of which are essentially identical to Soil Type 79E with the exception that Holyoke-derived soils dominate over bare rocky outcrops. Directly to the the southwest of the colony area, within the corridor of the powerline cut, the soil type is designated as Wilbraham and Menlo Soils, Extremely Stony (Soil Type 6). This soil type, too, is primarily derived from basalt, but also shale and sandstone. The exceptionally poor drainage offered by this substrate is probably why the land was chosen for use as a powerline cut, being essentially useless for any other type of development.
Colony Location and Statistics[edit]
The Westwoods Colony is located in the northwestern section of the Westwoods Trails in Guilford, Connecticut. The long, linear colony begins at 41.286718°, -72.716262° at the eastern end of the ledge and spanning west-northwest for approximately 320 feet to 41.287186°, -72.717182°.
- To view this location (eastern end as mentioned above) in Google Maps, click here.
Pertinent statistics concerning the location include:
- Elevation of Colony: Ranges from ~125 to ~145 feet above sea level
- Soil Type: Rock Outcrop-Holyoke Complex, 3 to 45 percent slopes (Soil Type 79E)
Pleasure Beach Park[edit]
Legend.[25]
Bridgeport, CT.[26]
Birdnote.[27]
Unconfirmed Colonies[edit]
The following locations are places which, based upon my research, most likely support a colony of Opuntia humifusa. In most cases, I have found relatively modern textual references and/or photographs (that is, resources which are less than 10 years old) that attest to the existence of O. humifusa in these locations. Only by an extreme disturbance to the plants or the habitat could these colonies possibly have vanished in the short amount of time that passed since they were last documented.
Most of these colonies are as yet undocumented because access to them is difficult. Some are to be found growing upon islands and are only accessible by boat. Others are found growing along the seashore on the mainland, but are difficult to investigate due to the fact that they are clearly on private land.
The goal of this study involves photo-documenting each one of these colonies. Thus, in time, every location listed here will ideally be migrated to the Confirmed Colonies section once I've had an opportunity to document them.
Outer Island Colony (Branford)[edit]
An issue of Connecticut Wildlife magazine published in 2003 notes that Outer Island, the island furthest south in the chain of thimble islands off the coast of Branford, "is a home for the state-endangered prickly pear cactus".[28] Notably, Outer Island is also part and parcel to the Stewart B. McKinney National Wildlife Refuge.
Although Outer Island is generally not open to ordinary visitation by the public, the 2012 schedule for ferry trips to the island can be found online at the website for the Friends of Outer Island.[29]
Russian Beach[edit]
As part of its online description of Russian Beach, the Town of Stratford website portrays a photograph of O. humifusa[30]. Presumably, the cactus can be found at Russin Beach. A map of Russian Beach, as well as access information, is available from the Connecticut Coastal Access Guide.[31]
Scott Cove Colony (Darien)[edit]
The presence of O. humifusa at Scott Cove in Darien, Connecticut was noted in a series of records dated November 9, 2010 which describe an application to build a residential dock in that cove.[32] The correspondence was produced by the Connecticut Department of Environmental Protection (CTDEEP) Office of Adjudications.
The investigation conducted by the CTDEEP found that special revisions to the application had to be made in order to protect "Eastern Prickly Pear, identified near the landward edge of the proposed dock". Based upon the proposed location of the dock, the cluster of O. humifusa is most likely at or within range of these coordinates: 41.059723°, -73.463757°. Further examination of the small cove using satellite imagery revealed other large rocky outcrops where O. humifusa may grow as well.
Because this site and the other potential habitat areas in Scott Cove are on private property, it will difficult to examine this colony.
Stratford Point[edit]
In an article published by the Connecticut Audubon Society (CAS) on June 16, 2011, strong populations of Opuntia humifusa are noted as living at the Audubon-managed Stratford Point Property in Stratford, Connecticut.[33] This population is further confirmed by another article published by the CAS in March 2012 which described a controlled burn of the grasslands at Stratford Point intended to prevent the succession of meadows into forest. Although the article text does not actually refer to O. humifusa, a supporting photograph that follows the text is given the caption," Walking the site - picking up litter, looking at what trees to avoid burning, and here clearing a bit of brush around the Prickly Pear Cactus marked by flagging behind the small cedar to protect it."[34]
Introduced Colonies[edit]
The colonies listed below are colonies which are known to be introduced into their current habitat. Presently, only the O. humifusa at Avery Point in Groton, Connecticut are confirmed to be introduced specimens. Because introduced specimens may live in areas where O. humifusa never existed historically, and because they may exhibit characteristics not found in native O. humifusa, they potentially have the ability to corrupt my research data. Therefore, these introduced colonies are not included in the scope my research.
Avery Point Colony (Groton)[edit]
In a publication produced by the Long Island Sound Study in August 2010, it was noted that two high school interns worked to remove invasive plants from the area of the Avery Point Lighthouse in Groton, Connecticut and that Opuntia humifusa, amongst other native plants, were established in their place.[35]
It is not known if these O. humifusa were established in a "natural setting" or a proper garden. Either way, these plants represent a known introduced colony and are therefore outside the scope of my research.
Inconclusive Explorations[edit]
A major portion of my survey of Connecticut's Opuntia humifusa involves attempting to locate colonies which were confirmed to have existed historically, but for which there is little or no modern data which confirms or denies their continued existence. Originally, this area of my research relied primarily upon the mention of O. humifusa in historic books (that is, books published at least 75 years ago). However, with the discovery of the George Safford Torrey Virtual Herbarium, my research focus has shifted to those places where botanists have historically collected professionally-verified specimens of O. humifusa.
While herbarium specimens are now the basis of my research and explorations, I have kept other historic references to certain colonies in the overviews below.
Naugatuck State Forest (Beacon Hill Area)[edit]
The presence of Opuntia humifusa in Beacon Falls, Connecticut is only known through historic records. This includes two herbarium specimens (one of which was collected in 1892 and the other collected most likely between 1900 and 1910), one brief reference in a book published in 1896 and one brief reference in a book published in 1910. From 1911 and onward, it would seem that no further mention of this colony has been made in any published literature, scientific or otherwise. Thus, it is difficult to say with any certainty whether or not this colony still exists.
Historic Information[edit]
The earliest, and the most reliable, record of Opuntia humifusa living in Beacon Falls, Connecticut comes from the George Safford Torrey Herbarium at UConn which contains a specimen of Opuntia humifusa collected by E. H. Eames on July 6, 1892.[36] The collection location is listed simply as "Beacon Falls". Of note, the herbarium specimen includes a flower bud, indicating that the plant collected by Eames was at least healthy enough to produce flowers.
The next reference to O. humifusa in Beacon Falls appears in The Town and City of Waterbury, Connecticut, Volume 1, published in 1896 by Sarah Johnson Prichard, which mentions that "the prickly pear is common on the summit of Beacon Hill, just south of the line of ancient Waterbury".[37]
Another specimen of O. humifusa can be found in the Yale University Herbarium (YPM CBS 016314)[38]. There is no collection date associated with the herbarium record. However, the collector of this specimen, H. S. Clark, was also the collector of specimens from other towns that date to 1903 and 1906. Thus, it is likely that the collection date of this specimen is in the same general timeframe between 1900 and 1910.
The latest reference to O. humifusa living in Beacon Falls occurs in a 1910 publication, "Catalogue of the Flowering Plants and Ferns of Connecticut Growing Without Cultivation", authored by Charles Burr Graves. Graves briefly mentions that O. humifusa can be found in "Naugatuck and Beacon Falls".[39] Graves attributes this assertion to J. K. Goodrich, though I have been unable to find any published material by Goodrich which might provide further information.
Preliminary Assessment[edit]
Examination of satellite imagery of Beacon Hill area reveals several promising locations for the presence of O. humifusa. The area of Beacon Hill is now contained within the Naugatuck State Forest. Entrance to the state forest is via a blue-blazed trail. However, the trail itself does not pass through the promising habitat areas. If unmarked side trails aren't present from the blue-blazed trail, then considerable bush-whacking will be required to explore the potential habitat areas.
Exploration[edit]
April 19, 2012[edit]
On April 19, 2012, I conducted an on-site exploration during which I thoroughly inspected roughly 30% of the possible habitat areas that I originally identified on Beacon Hill through examination of satellite imagery.
The promising areas that I explored are essentially high-elevation clearings on the southwestern slopes of Beacon Hill where the bedrock is exceptionally close to the surface. Tree growth was minimal on these patches due to a lack of soil and, perhaps, harsh environmental conditions. This presented at least two promising factors for the existence of O. humifusa. First of all, the elevation of these areas means that they are, more than likely, slightly warmer than the surrounding valleys (where colder air is apt to pool). Second, the openness of the clearings offers considerable exposure to sunlight.
May 5, 2012[edit]
A second exploration was conducted of promising areas further west-southwest of the original exploration area. Another 30% to 40% of the potential habitat locations was investigated, most of which was essentially similar to the habitat discovered during my first exploration. Again, no evidence of 'O. humifusa' presence could be located.
Status[edit]
I have not explored all of the possible locations on Beacon Hill where O. humifusa may currently live. However, I have thoroughly examined a very large percentage of those areas (at least 60% to 70%). Because the remaining unexplored locations are in close proximity to the areas that I have already explored, and because the the unexplored areas most likely share similar or nearly identical habitat conditions, I am skeptical that O. humifusa still lives on Beacon Hill.
Until I explore every individual ledge on Beacon Hill, however, I will not be able to say for certain that O. humifusa is extinct on that mountain. My examination of confirmed colonies of O. humifusa in both Plainville and New Haven has revealed that the plant may flourish in extremely isolated areas despite being in very close proximity to relatively large areas of similar habitat. Therefore, it is entirely possible that one of the few ledges on Beacon Hill which I did not investigate may contain a colony of O. humifusa which, for one reason or another, has been unable expand its range to similar habitats on nearby ledges.
Exploration Location[edit]
This exploration involved an improvised loop hike of approximately 2.88 miles throughout the Naugatuck State Forest in the area of Beacon Hill in Beacon Falls, Connecticut. Please note that the habitat area which I explored was not found along the widely-used blue-blazed trail. Reaching the exploration area on the southwestern slope of Beacon Hill required considerable hiking on trails which aren't seen in the CFPA map of Naugatuck State Forest. Bush-whacking was also necessitated in some instances.
- To download the GPS tracklog of this exploration (KML format), click here.
Possible Explanations for Absence[edit]
Given that the presence of Opuntia humifusa in Beacon Falls between the 1890s and early 1900s is confirmed, there are two distinct possibilities that might explain my inability to locate any of the cacti in modern times.
Imprecise Historical Literature[edit]
For one, the herbarium specimens of O. humifusa are the primary pieces of evidence confirming their presence in Beacon Falls. However, neither of these herbarium records actually state that the plants were found on Beacon Hill; they simply relate the collection location as "Beacon Falls". Hypothetically, this could mean that the herbarium specimens were harvested anywhere within the boundaries of Beacon Falls.
The single piece of historical literature which actually pinpointed the location of O. humifusa on Beacon Hill was Prichard's book on the history of nearby Waterbury. While Prichard may have been fairly knowledgeable on the topic of Waterbury, there is no evidence that she possessed the same depth of knowledge concerning neighboring Beacon Falls. It may well be that when Prichard wrote that "the prickly pear is common on the summit of Beacon Hill, just south of the line of ancient Waterbury", she was simply using Beacon Hill as a general landmark with which most people of that day would be familiar. It could well have been that the cacti never actually existed on Beacon Hill, but instead existed on some unnamed hill within the same general region. Prichard would simply have referred to it as "Beacon Hill" for lack of a better-known landmark. In that case, it is possible that the cacti could instead exist on or around the bald cliffs to the west (on the opposite side of Route 8). I have yet to investigate this alternate location, but will do so as time permits.
Local Extirpation[edit]
Perhaps a more likely scenario is that O. humifusa did in fact exist on Beacon Hill between 1890 and 1910, and that it may have continued to flourish for some decades afterwards. We can assume that Beacon Hill probably would have been sparsely wooded around the turn of the 20th-century, perhaps even largely devoid of trees. The area of Beacon Hill may well have been cleared to some degree to make room for pasture land and, to a lesser degree, for lumber. The lack of competition from trees on Beacon Hill would've meant that cacti could take advantage of full sun on the well-drained soil upon the mountain.
However, as the case has been with most old pasture land in Connecticut, the use of Beacon Hill as a grazing area would have expired no later than the very early 1900s, perhaps earlier. In the time that followed, trees would have been able to begin taking root and growing, eventually culminating in the mature forest and solid woodland canopy that covers the mountain today. If this scenario is correct, and it seems that it is, this would mean that the cacti documented on Beacon Hill in the 1890s and early 1900s would have ultimately been doomed. With each passing decade, the tree cover would've expanded and thickened. In time, any colonies of O. humifusa living upon the mountain would literally have been shaded out. Perhaps they could've persisted in the light shade of younger trees for a decade or two, but as the canopy grew more dense, cutting off light to the ground, the cacti would've first lost their ability to flower, and then lost their ability to gather enough sunlight nourish themselves. At that point, the cacti would've perished fairly quickly, leaving behind no evidence of their presence.
Although this scenario comports quite closely with the known agricultural and ecological history of the Connecticut landscape, what evidence is there that conclusively suggests this pattern of local extirpation actually occurred?
For one thing, aerial photography from the early 1930s reveals that the forest upon Beacon Hill was still somewhat sparse by comparison to the modern forest we see today. In fact, there were still some cleared parcels of land upon the hill which appear to have been farms of some kind (perhaps tree farms). Thus, we know that only sparse forest existed on Beacon Hill some 20 to 30 years after O. humifusa was documented there. The presence of sparse forest could hypothetically be explained in various ways. For example, it could have been that the forest was thinned for lumber in the late 1920s. Perhaps a forest fire tore through the forest in the 1910s, leaving only select fire-hardy trees. Although these possibilities cannot be ruled out, they aren't especially likely. In the 1920s, it is more probable that a lumbering venture would've simply clear-cut the entire area rather than merely thinning the forest. The notion that a forest fire thinned the forest is perhaps plausible, but I cannot find any historical evidence of such an extensive forest fire in that area. It is most probable that the sparse forest was actually just immature forest; the result of young "pioneer" trees growing upon land that had been entirely clear of significant tree growth at least one or two decades earlier.
Unsuccessful Explorations[edit]
Powerline Cut (Middletown)[edit]
On May 17, 2012, I conducted an exploration of 1.14 miles of terrain (~2.3 mile out-and-back hike) along a powerline cut in Middletown, beginning at Bartholomew Road and terminating at Route 9. The terrain along the powerline cut is a combination of meadow and rocky outcrops with elevations concentrated between 450 and 550 feet above mean sea level (AMSL), though maximum elevation reaches approximately 580 feet AMSL and minimum elevation drops as low as 330 feet AMSL.
This exploration was launched after I spotted dry, rocky outcrops beside the road while driving along Route 9 in Middletown. I thought I had seen a few Juniperus virginiana (Eastern Red Cedar) which, in combination with the xeric, rocky character of the powerline cut, seemed to suggest it may offer suitable habitat for Opuntia humifusa.
After a very thorough investigation of all of the rocky outcrops along the full-length of the powerline cut, I have not discovered any evidence of O. humifusa. In addition, the coniferous trees I had seen were confirmed not to be Juniperus sp.
The rocky outcrops along the powerline did seem suitable as cacti habitat, offering xeric conditions with well-drained soil and full exposure to sunlight.
A post-exploration review of soil types present along the powerline cut revealed a rather broad diversity of soil types which weren't necessarily known to be conducive to O. humifusa. These soil types included Catden and Freetown soils (Soil Type 18), Timakwa and Natchaug soils (Soil Type 17), Charlton-Chatfield complex (Soil Type 73E), Ridgebury, Leicester, and Whitman soils, extremely stony (Soil Type 3), Hollis-Chatfield-Rock outcrop complex (Soil Types 75C and 75E). At the time of the exploration, none of these various soil types had been observed at known O. humifusa habitat in Connecticut. My later discovery of the Ingham Hill Colony, however, indicates that Charlton-Chatfield Complex does, in fact, provide suitable soil for O. humifusa.
High Rock Mountain (Bethany & Hamden)[edit]
On May 19, 2012, I conducted an exploration of rocky outcrops on High Rock Mountain, accessible along the blue-blazed Quinnipiac Trail. I accessed the trail from Brooks Road in Bethany and hiked the Quinnipiac Trail to the bald ridges on High Rock Mountain in Hamden (~2.75 mile loop hike).
My prior research suggested that High Rock Mountain offered excellent habitat for O. humifusa. The rocky outcrops consist entirely of Holyoke-Rocky Outcrop Complex (Soil Types 78C and 78E), a soil type known to be associated with all confirmed O. humifusa sites in New Haven, Hamden and Plainville. The rocky outcrops that I investigated are also designated by CTECO GIS maps as Subacidic Rocky Outcrops (SubRSO), a critical habitat type with which O. humifusa is closely associated in both New Haven and Hamden on West Rock Ridge. In addition, these rocky outcrops on High Rock Mountain are less than one mile from large colonies of O. humifusa that I've observed in Hamden at the northern extent of West Rock Ridge State Park. When factored together, all of these characteristics seemed to indicate a very high probability of O. humifusa colonization on High Rock Mountain.
The entire exploration, however, revealed no evidence of O. humifusa on High Rock Mountain.
The rocky outcrops that were targeted during my exploration exhibited the presence of Juniperus virginiana (Eastern Red Cedar), a known indicator species of O. humifusa on this type of terrain. This raised the probability of finding O. humifusa even higher.
However, if any feature of this terrain was inconducive to O. humifusa, it was a lack of full exposure to sunlight. The rocky outcrops on High Rock Mountain were too tightly crowded by forest, leaving little room for the shade-intolerant O. humifusa to take hold. There were a few areas which offered sufficient sunlight exposure, but they were few and far between. In addition, it seemed that many of the larger, exposed areas were home to an unusually high diversity of herbaceous plants which would probably out-compete O. humifusa.
Other Historical Locations[edit]
Below is a list of towns where Opuntia humifusa was found historically. This information is derived primarily from herbarium records, but also historical books. All of the supporting resources referenced here are at least 10 years old, but most are considerably older (many are greater than 100 years old).
It is entirely possible that, in some cases, the historical colonies from which these specimens were collected correspond with extant colonies that I have documented. However, because all of the historical resources listed here refer to collection locations so vaguely, it is difficult or impossible to say for sure. For example, in 1822 a botanist by the name of H. N. Fenn collected a specimen of O. humifusa from New Haven, Connecticut. Since Fenn did not include specifics about the collection location, it is impossible to say whether or not he harvested his specimen from the earlier ancestors of the modern populations at West Rock Ridge (which I have documented) or from some different location where O. humifusa no longer exists. For this reason, the historical data presented below occasionally overlaps with towns at which I have documented modern O. humifusa colonies.
There is little or no information available that can confirm or deny the continued existence of O. humifusa at some of the towns listed below. These places include Scotland, Naugatuck, Oxford, Seymour and Wilton. O. humifusa undoubtedly grew wild at one time in these municipalities, but no record of the continued existence of the cactus have been found in over a century. The only way to know for sure would involve a thorough exploration of all possible habitat area in those towns (a task which could easily take years).
Branford (General Area, Stony Creek & Kelsey Island)[edit]
The Yale University Herbarium contains a specimen of Opuntia humifusa collected in Branford, Connecticut by W. H. Brewer in 1852 (YPM YU 051550).[38] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium contains a second specimen of Opuntia humifusa collected at Stony Creek by J. H. Buell on July 1, 1874 (YPM YU 051549)[38]. Stony Creek is not an incorporated town in Connecticut, but rather a census-designated place within Branford. No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia humifusa collected in Branford on September 22, 1998 by William H. Moorhead III in Branford, Connecticut (CONN Accession #122327). The collection location is rather precisely revealed as "sunny outcrops of pink bedrock (mapped as granitic gneiss)" on the "northeast end" of Kelsey Island.[40] The elevation of the collection site is recorded as being 3 meters (9.8 feet) above sea level. Moorhead elaborates even further, noting that the O. humifusa plants from which he harvested fruits were "on sub-level to gently moderately sloping surfaces." Interestingly, he adds that O. humifusa can also be found "in similar habitat at northern end of smaller upland island northwest of main island, and in house yards on mainland north of island." Since the collection date for this specimen is relatively recent, there is a very good possibility that the cactus colony from which it was harvested still exists.
Bridgeport[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia vulgaris collected on July 7, 1909 by E. H. Eames from a "dry exposed ledge" in Bridgeport, Connecticut (CONN Accession #105615). The elevation of the collection site is noted as 3 feet above sea level.[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Burlington (Burlington Mountain)[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia humifusa collected on July 25, 1908 from Burlington, Connecticut (CONN Accession #101928). The collection location is further identified as Burlington Mountain.[40]
In modern times, it doesn't appear that there is any landform known officially as Burlington Mountain within the town, a fact which complicates the task of trying to determine where this colony would have existed over a century ago. Historical maps from the mid-1800s don't show any labelled landmark by the name of "Burlington Mountain", even though Burlington Mountain is referred to briefly in a few texts dating the first decade of the 20th century. None of the historic texts provide any clues at what modern mountain was once called Burlington Mountain.
Clinton[edit]
The Yale University Herbarium contains a specimen of Opuntia humifusa vulgaris collected in Clinton, Connecticut by J. H. Buell on August 7, 1960 (YPM CBS 016311). No further specifics are provided concerning the location of the colony from which the specimen was harvested.[38]
Franklin[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia vulgaris collected on May 11, 1916 from "rocky open woods" in Franklin, Connecticut (CONN Accession #161634).[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Guilford (General Area & Leetes Island)[edit]
The Yale University Herbarium contains a specimen of Opuntia humifusa vulgaris collected in Guilford, Connecticut by C. H. Bissell on July 16, 1897 (YPM CBS 016313)[38]. No further specifics are provided concerning the location of the colony from which the specimen was harvested.
In a 1910 publication titled "Catalogue of the Flowering Plants and Ferns of Connecticut Growing Without Cultivation", author Charles B. Graves notes Guilford as a town known to support wild O. humifusa at that time.[39] Graves also separately mentions North Guilford, however there is no such incorporated town in Connecticut and he was likely referring to the northern sections of Guilford.
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia humifusa collected in Guilford, Connecticut on August 27, 1950 by G. S. Torrey (CONN Accession #161634). The collection location is described as "ledges in scrubby pasture" at Leetes Island.[40] The record also notes that this collection was performed with the Connecticut Botanical Society, which may possibly still have field records pertinent to this O. humifusa colony.
Milford[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia rafinesquii collected on July 7, 1893 by E. H. Eames from "dry soil on rocks" in Milford, Connecticut (CONN Accession #161629).[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Because such vague location data is provided with this specimen, it is difficult to say whether or not Eames harvested this specimen from the same colony that I've confirmed to exist currently in Milford (Milford Point Colony). It is unlikely, however, because the Milford Point Colony is not at all rocky.
Naugatuck[edit]
The Yale University Herbarium contains a specimen of Opuntia humifusa vulgaris collected in Naugatuck, Connecticut by A. E. Blewitt on May 30, 1907 (YPM CBS 016310). No further specifics are provided concerning the location of the colony from which the specimen was harvested.[38]
In a 1910 publication titled "Catalogue of the Flowering Plants and Ferns of Connecticut Growing Without Cultivation", author Charles B. Graves notes Naugatuck as a town known to support wild O. humifusa at that time.[39]
New Haven[edit]
The Yale University Herbarium contains a specimen of Opuntia humifusa collected in New Haven, Connecticut by H. N. Fenn in 1822 (YPM YU 070465).[38] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium contains a specimen of O. humifusa collected in New Haven, Connecticut in July 1886 (YPM YU 051546).[38] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium contains a specimen of O. humifusa collected at "Lighthouse Point" in New Haven, Connecticut by L. Brown on August 23, 1988 (YPM YU 051547).[38] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Old Lyme (General Area & McCurdy Road)[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia vulgaris collected in Old Lyme, Connecticut on April 21, 1941 by Wilfred J. Latham (CONN Accession #161630).[40] The elevation of the collection site is noted as 26 feet above sea level. No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium contains a specimen of Opuntia humifusa vulgaris collected in Old Lyme, Connecticut by T. O. Hendrickson on September 29, 1988 (YPM CBS 016309). No further specifics are provided concerning the location of the colony from which the specimen was harvested.[38]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia compressa collected in Old Lyme, Connecticut on June 8, 1996 by Leslie John Mehrhoff. The collection location is rather precisely revealed as the "east side of McCurdy Road near entrance to Old Lyme Country Club".[40] Since the collection date for this specimen is relatively recent, there is a good possibility that the cactus colony from which it was harvested still exists. However, the fact that the specimen was collected from the "Old Lyme Country Club" suggests that it may have been from a cultivated garden.
Oxford[edit]
In a 1910 publication titled "Catalogue of the Flowering Plants and Ferns of Connecticut Growing Without Cultivation", author Charles B. Graves notes Oxford as a town known to support wild O. humifusa at that time.[39]
Scotland[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia vulgaris collected on May 10, 1906 by Hugh S. Clark in Scotland, Connecticut (CONN Accession #05903). The elevation of the collection site is noted as being 279 feet above sea level.[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium contains a specimen of Opuntia humifusa vulgaris collected in Scotland, Connecticut by C. H. Bissell on May 30, 1906 (YPM CBS 016312)[38], only 20 days after Clark harvested his own specimen from Scotland. No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Finally, in a 1910 publication titled "Catalogue of the Flowering Plants and Ferns of Connecticut Growing Without Cultivation", author Charles B. Graves notes Scotland as a town known to support wild O. humifusa at that time.[39]
Seymour[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia vulgaris collected on June 7, 1903 by H. S. Clark in Seymour, Connecticut (CONN Accession #161633). The elevation of the collection site is noted as being 102 feet above sea level.[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium also contains a specimen of Opuntia humifusa collected in Seymour, Connecticut by H. S. Clark (YPM CBS 025967)[38]. No further specifics are provided concerning the location of the colony from which the specimen was harvested. No date is associated with this specimen, however it may well have been collected the same day as the specimen contained in the Torrey Herbarium.
In a 1910 publication titled "Catalogue of the Flowering Plants and Ferns of Connecticut Growing Without Cultivation", author Charles B. Graves notes Seymour as a town known to support wild O. humifusa at that time.[39]
Stratford (General Area & Housatonic River)[edit]
The Yale University Herbarium contains a specimen of Opuntia humifusa collected in Stratford, Connecticut by A. L. Winton in June 1883 (YPM YU 051548)[38]. No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium contains a specimen of Opuntia humifusa collected in Stratford, Connecticut by C. H. Bissell on July 17, 1901 (YPM CBS 025966)[38]. No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia vulgaris collected on September 10, 1904 "near [the] Housatonic River" in Stratford, Connecticut (CONN Accession #05904).[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
The Yale University Herbarium contains a specimen of Opuntia humifusa collected in Stratford, Connecticut by D. C. Tank on May 19, 2007 (YPM YU 100036)[38]. No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Westbrook[edit]
The George Safford Torrey Herbarium at UConn contains a specimen of Opuntia vulgaris collected on April 16, 1934 by Howard Merrill from "rocky sterile soil" in Westbrook, Connecticut (CONN Accession #161632). The elevation of the collection site is noted as being 36 feet above sea level.[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Westport[edit]
The George Safford Torrey Herbarium at UConn contains two specimens of Opuntia vulgaris collected on May 1, 1909 by E. H. Eames from an "exposed ledge" in Westport, Connecticut (CONN Accession #105616 and #04642). The elevation of collection site is stated as 30 feet above sea level.[40] No further specifics are provided concerning the location of the colony from which the specimen was harvested.
Wilton[edit]
The Connecticut Botanical Society Herbarium contains a specimen of Opuntia humifusa ssp. vulgaris collected in Wilton, Connecticut by Anna E. Carpenter on July 11, 1924 (CBS.016308). No further specifics are provided concerning the location of the colony from which the specimen was harvested.[41]
Theories & Unanswered Questions[edit]
Perhaps the most surprising discovery throughout the course of my explorations for Connecticut's Opuntia humifusa (aside from the cacti themselves) has been the realization that remarkably little is known about this cactus. Thus, one of the goals of my research has been to try and better understand the ecology of these cacti in Connecticut through observing them directly.
Below are a series of questions and tentative answers that I've assembled. In most cases, I can offer only observations, suggestions and theories.
How did it get there?[edit]
What accounts for the ability of a colony of O. humifusa to exist as far as 20 miles from the nearest neighboring colony? How did the cactus make such a huge leap without any intermediate colonies?
Granted, this questions seems rather simple. But, the fact of the matter is that surprisingly minimal research has been invested in answering this question. Furthermore, the answer is exceptionally important in understanding the fragmented and sometimes boggling distribution of O. humifusa in Connecticut.
Before I begin, I'll briefly clarify that there are only two basic ways that O. humifusa can produce independent off-spring. The first is vegetative, meaning that whenever a cladode becomes detached from the parent plant and hits the ground, it stands a fair chance of sinking its own roots and becoming an independent plant. The second method is by seed. The fruits, or "pears", of O. humifusa contain seeds and wherever the fruits go, the seeds accompany.
First off, we know that the wind is not strong enough to carry a detached cladode or fruit more than perhaps a foot or two from the parent plant. Under extremely windy conditions, with the right topography, perhaps the wind could move plant pieces even further; I'll say a maximum of 10 to 15 feet, though that would truly exceptional. This mechanical force may be sufficient to push a detached cladode or fruit over a nearby cliff, at which point it might land on a rocky terrace and begin a new colony. But certainly, the wind cannot carry a cladode for any significant distance across a landscape. So, we can say with certainty that O. humifusa does not disperse long distances of its own ingenuity, in the sense that a dandelion can potentially fly its kite-like seeds for several miles.
Second, I have frequently observed droppings amongst O. humifusa colonies which appear to be from small mammals, most likely rabbits. And, indeed, studies in Kansas in the 1940s revealed that rabbits were known to feed upon both the fruits and cladodes of O. humifusa[42]. However, the study observed that rabbits tended to limit their consumption of the cactus to those times when food was particularly scarce, when perhaps the hardy, evergreen O. humifusa might be the only green plant matter available. Furthermore, I cannot say that I have noticed any extensive evidence that Connecticut O. humifusa are subject to consumption by small mammals. In most cases, the cladodes of O. humifusa that I've observed are in remarkably pristine condition. Even if we were to entertain that at some point in the past there was a serious enough food shortage in Connecticut for cottontail rabbits to begin gnawing on O. humifusa plants, the potential for dispersal by this method is not exceptionally great. Rabbits aren't likely to detach cladodes and haul them any significant distance, and even if they did, it is further unlikely that they would lose interest in it before consuming enough to kill the vegetative potential of the broken stem. But then there is the possibility that the seeds of the O. humifusa pears, after being consumed, might pass through the digestive system of rabbits and be deposited elsewhere. This is a plausible means of dispersal to which I am open, but it still cannot explain how O. humifusa might travel a distance of several miles over rough terrain. The home range of any rabbit is typically restricted to a relatively small area, and no species living in Connecticut are known to migrate long distances.
The most promising theory is that O. humifusa is distributed long distances chiefly by birds. Birds have long been observed to consume the pears of O. humifusa and other species of Opuntia found elsewhere in the world. In fact, studies have shown that seeds which first pass through the digestive system of an animal will germinate more reliably and more quickly than those that simply fall from the cactus in an unscathed pear[9]. Since birds can potentially travel enormous distances over terrain that would be challenging for terrestrial animals, as well as deposit their droppings from the air in relatively random locations, it becomes clear that birds must have played a decisive role in distributing O. humifusa across Connecticut.
When we add birds to the equation, there ceases to be any mystery behind how O. humifusa might have appeared on a high ledge along a ridge or in an isolated glade deep within the forest. While all of these locations seem like relatively inaccessible locations to man and other mammals, they are simply another place for traveling birds to land or "lighten the load", so to speak, while flying high above.
Why aren't they there?[edit]
Another question that is sometimes puzzling is why, within fairly large stretches of potentially excellent habitat, there seems to be no trace of O. humifusa. The answer to this question is three-fold.
To begin with, even though birds offer the most promising mode of dispersal for O. humifusa, a substantial amount of luck is required for this dispersal mechanism to succeed. Distribution by birds occurs when they defecate, depositing the seeds in their waste. But birds are in no way selective about where they choose to defecate, generally doing so whenever the urge strikes, either while they are flying or while they are perched. When you consider the very specific habitat requirements of O. humifusa, it is no surprise that the vast majority of O. humifusa seeds are deposited in bird droppings in habitat areas that entirely incompatible with the needs of the cactus. Only by sheer luck will a bird that has been feeding on cactus pears happen to defecate in a spot which satisfies all of the criteria for those seeds to give rise to a mature plant (well-drained soil, full sun, minimal competing plants).
But let's say that a given seed, despite the overwhelming odds, is deposited by a bird on a perfect traprock ledge in Connecticut, replete with sandy soil and full sunlight. Even still, there is only about a 25% chance that the seed will prove viable. A number of factors can influence the relatively low likelihood of O. humifusa being dispersed to a wholly new habitat area, such as the following:
- 50% of the seeds produced by O. humifusa aren't eaten in the first place
- 95% of the seeds consumed by birds are dispersed in unsuitable habitat
- 75% of the seeds that are deposited on ideal habitat will not actually germinate
Considering all of these factors, there would only be a 0.75% chance that any given seed will be eaten by a bird, deposited on good habitat and actually germinate. And, in truth, everyone of the above estimated percentages is probably far too optimistic in favor of O. humifusa. If we were more skeptical in all three of the cases above, then the adjusted chance of successful dispersal and germination for any given seed would probably be significantly lower.
Furthermore, we must consider that even those seeds which have successfully germinated are then subject any number of disturbances, for the resilience attributed to mature O. humifusa plants does not necessarily extend to small, immature specimens. A newly-sprouted cactus will spend much of its first growing season barely larger than a thimble; it might incidentally be trampled by a hiker, crushed beneath a fallen tree branch, consumed by insects, or freeze to death during an unusually extreme cold snap during its first winter. When we factor this into the odds, the likelihood that a given O. humifusa plant will produce a seed which will be consumed by a bird, dispersed to a new habitat area, germinate and ultimately mature into a large, healthy, resilient plant are probably disparagingly low... somewhere in the range of 1:10,000 and 1:100,000). Thus, it is understandable that it could take decades, perhaps even centuries, for O. humifusa to become established in new territory. It is partially for this very reason that the cactus receives recognition as a Connecticut Species of Special Concern, for the destruction of a given colony in a certain town may very well mean that O. humifusa will be gone from that place for an extremely long time before it can be re-colonized. In fact, the undeveloped landscapes of many towns have become so thickly reforested in the last 150 years that the remaining available habitat for O. humifusa is incredibly small; in these cases, if the existing cactus population was lost, the likelihood of re-colonization from a coastal colony is so low that, for all intents and purposes, it would be appropriate to declare them permanently extirpated from those towns.
In many cases, areas devoid of cacti that would seem to present excellent habitat have likely experienced considerable changes to the face of the landscape over the last 150 years, meaning that suitable habitat may not have existed even in very recent history. Powerline cuts, for example, oftentimes offer what would seem to be remarkably good habitat the cactus, but despite all of my research and a few field explorations, I have found no evidence that O. humifusa has been capable of colonizing these areas yet. It may simply be that these features of the landscape were too recently constructed and that the long-range dispersal characteristics of O. humifusa prevent it from quickly taking advantage of these places.
How can colonies at the coastline become so well-dispersed?[edit]
If we consider the two questions and answers above, it is clear that O. humifusa colonizes new habitat areas very, very slowly. But if we should believe the above assertions to be accurate, then how can a stronghold such as the Long Beach Complex possibly exist? To summarize, the Long Beach Complex includes literally hundreds of cacti scattered over upon a 1.5-mile stretch of the Long Beach Peninsula. If O. humifusa has so aggressively colonized Long Beach, why can't it do the same elsewhere? The answer to this question rests solely upon a series of beneficial conditions which converge on the Long Beach Peninsula to truly favor the expansion of O. humifusa.
For starters, we have already established that birds are the primary vector for O. humifusa seed dispersal. In the case of inland colonies, the species of birds that feed upon pears, as well as the frequency with which the plants are visited, is probably extremely variable. Coastal areas, however, have served as nesting sites of various seabirds since prehistory. These coastal nesting sites, which include Long Beach Peninsula, offer unusually high numbers of nesting birds which are tethered to the immediate landscape for several months at a time. This means that, wherever nesting sites host a population of O. humifusa, the cacti are literally at the dead-center of a dispersal hotspot where pears are routinely foraged by resident seabirds.
Furthermore, unlike inland sites that are typically surrounded by thick woodlands, coastal sites such as Long Beach offer an extremely high ratio of suitable habitat per acre. Long Beach Peninsula is ripe with wide swaths of open dunes and scrubland, all of which are steeped in direct sunlight and enjoy wintertime low temperatures that are slightly warmer than those experienced at inland locations. In short, the majority of the landscape on coastal sites tends to be accommodating of the needs of O. humifusa, while a comparatively minute percentage of the inland landscape can provide for the complex needs of the cactus.
Let's consider these more optimal conditions in the same format that we considered them above:
- 25% of the seeds produced by O. humifusa aren't eaten in the first place
- 40% of the seeds consumed by birds are dispersed in unsuitable habitat
- 75% of the seeds that are deposited on ideal habitat will not actually germinate
As we can see here, the higher population and longer residence of birds, when coupled with the abundance of suitable cactus habitat, means that the rate of successful short-distance dispersal and germination increases to roughly 11% on coastal sites like Long Beach Peninsula. While not staggeringly high, this represents a drastic increase over dispersal rates experienced inland. Thus, the abundance of O. humifusa on Long Beach Peninsula can be explained as an example of a series of ecological conditions which conspire to help O. humifusa thrive to a degree that is otherwise unthinkable in most other environments.
Why are some inland colonies so isolated despite abundant habitat very nearby?[edit]
This may seem to be a repetition of a question that has already been discussed. However, while our previous question focused on reasons why some large area of habitat may not have any cacti, this question focuses on why seemingly suitable habitat areas that are in very close proximity to a known colony would still be oddly devoid cacti. For example, if an established colony of O. humifusa lives upon a south-facing ledge on a traprock ridge, why would the seemingly identical ledge only 60 feet away be devoid of the cactus?
The simplest explanation, which I suspect contributes only partially to this phenomenon, relates to all of the aforementioned difficulties in dispersal which I've already discussed. Even if a suitable ledge is only 40 feet away, the random and rather unreliable nature of dispersal by birds mean that the ledge might as well be a mile away... or several miles away... and still possess a nearly equal likelihood of being colonized. However, I would submit that in many of these cases, the supposedly "identical" nearby ledges aren't actually as identical as they might seem to an ordinary observer.
While it is true that the majority of inland cacti colonies are found upon traprock ledges, we must temper this finding with the observation that an overwhelming majority of traprock ledges in Connecticut do not, and never have, supported colonies of O. humifusa. I interpret this as an indication that traprock ridges generally do not offer suitable habitat for the cactus.
As we know, O. humifusa has a series of requirements that must be met in order thrive in a given habitat. They are as follows:
- Temperatures should not drop below 0°F. If they do, it should be an exceptionally rare occurrence which takes place only once every few years. Otherwise, young cacti would probably die before becoming firmly-established enough to weather these rare cold spells.
- At least six hours of unobstructed sunlight must be available every day. Established cacti can tolerate as little as perhaps four hours, but young plants would suffer considerable stress and growth deformities with such reduced light exposure.
- Neighboring trees and competing plants must not be capable of obstructing sunlight. See #2 above.
- Soil must be very well-drained. Any places where water dwells for even 24 hours after a heavy rainfall are entirely unsuitable for O. humifusa. Such conditions lead to rotting of the roots, a phenomenon that will quickly kill even large, mature cacti.
- Soil must be voluminous enough for cacti to firmly take root. Although I've observed O. humifusa growing on a 1/4"-thick mat of dried lichen upon an otherwise bare rock face, such plants are unlikely to ever reach an advanced state of development. Bare rock is NOT a suitable habitat for O. humifusa. All colonies found on rocky outcrops inhabit an area of the outcrop where at least some soil has accumulated.
- Soil must be stable. In habitats where the dirt or sand can easily be moved about by wind and water, the cacti will be severely stressed, either by being periodically buried or by having their roots periodically exposed.
Given these strict criteria, it's almost amazing that any traprock ridges are capable of supporting O. humifusa. And, indeed, most of Connecticut's inland ridges and rocky outcrops are decidedly unsuitable. These are habitat areas in Connecticut where O. humifusa is truly braving the fringes of its range and battling conditions which routinely conspire to destroy its presence. A scant few ledges scattered throughout the state possess the delicate balance of factors that produce a micro-climate that is conducive to the cactus. Even if a certain ledge meets 5 of the 6 criteria listed above, it still will probably prove unsuitable for O. humifusa. In such harsh, borderline environments, every aspect of the habitat area must fall within an extremely narrow range of acceptable tolerances.
So, while nearby ledges may seem to be practically identical to the plain sight, there could be any number of minute variations in temperature, drainage, available sunlight and available soil which might make them unsuitable in comparison... even if they are only 20 to 100 feet away from a firmly-established colony.
When we examine the local isolation of inland colonies in light of the slow dispersal rate and complex habitat criteria of O. humifusa, it is clear that "jumping" to a nearby ledge is no easy task. In many cases, it may well be impossible since the plant cannot live on the nearby ledge because the temperature drops slightly lower, because the soil is too unstable, the sunlight is limited by neighboring trees, etc, etc.
References[edit]
- ↑ Wallace, W. Seward. "Prickly Pear on Hook Mountain." Popular Science. Nov 1900: n. page. Print. <http://books.google.com/books?id=BRtbAAAAYAAJ&printsec=frontcover>.
- ↑ 2.0 2.1 2.2 Abella, Scott R., and John F. Jaeger. Ecology of Eastern Prickly Pear Cactus (Opuntia Humifusa) in Oak Openings Preserve, Northwestern Ohio. Ann Arbor, Michigan: University of Michigan Library, 2004. Print. <http://hdl.handle.net/2027/spo.0497763.0043.101>.
- ↑ 3.0 3.1 3.2 Wallace, Robert S., and David E. Fairbrothers. "The New England Distribution of Opuntia humifusa (Raf.) Raf." Rhodora: Journal of the New England Botanical Club. 89.859 (1987): 327-332. Print. <http://ia600704.us.archive.org/20/items/cbarchive_35776_thenewenglanddistributionofopu9999/thenewenglanddistributionofopu9999.pdf>.
- ↑ 4.0 4.1 VanDerWal, Jeremy J., and Lesley Lovett-Doust. Habitat definition of Opuntia humifusa using seedling transplants along a successional gradient at Point Pelee National Park. Department of Biology, University of Windsor, 2003. Web. <http://web4.uwindsor.ca/users/b/b87/GARP.nsf/bab13a777f84009f85256ea600759a11/48edd5d31581e083852570350048e9f3/$FILE/Habitat Definition report 2003.pdf>.
- ↑ Läuchli, André, and Ulrich Lüttge. Salinity: Environment - Plants - Molecules. Springer, 2002. 342. Print.<http://books.google.com/books?id=eZzqw9HUbW8C&pg=PA342&dq=humifusa+cactus&hl=en&sa=X&ei=cwDFT6upJ7PJsQK5xsHgCQ&ved=0CEoQ6AEwAzgy#v=onepage&q=humifusa%20cactus&f=false>
- ↑ "Soil Survey of the State of Connecticut." Connecticut Environmental Conditions Online. University of Connecticut, n.d. Web. 18 May 2012. <http://www.cteco.uconn.edu/docs/usda/connecticut.pdf>.
- ↑ "Connecticut Critical Habitats." Connecticut Environmental Conditions Online. University of Connecticut, Mar 2011. Web. 18 May 2012. <http://www.cteco.uconn.edu/guides/resource/CT_ECO_Resource_Guide_Critical_Habitat.pdf>
- ↑ Nobel, Park S. Environmental Biology of Agaves and Cacti. Cambridge: Cambridge University Press, 2003. 161. Print. <http://books.google.com/books?id=jdO2U84I6JwC&pg=PA161&dq=humifusa+cactus&hl=en&sa=X&ei=-ePET5mWJerDsQKy9ZzQCQ&ved=0CDcQ6AEwADgU#v=onepage&q=humifusa%20cactus&f=false>.
- ↑ 9.0 9.1 Taylor, Jane. "Species: Opuntia humifusa." U. S. Forest Service: Fire Effects Information System. United States Forest Service, 2005. Web. 31 May 2012. <http://www.fs.fed.us/database/feis/plants/cactus/opuhum/all.html>.
- ↑ "Endangered, Threatened & Special Concern Plants." Connecticut Department of Energy and Environmental Protection. Connecticut Department of Energy and Environmental Protection, 1 Jul 2010. Web. 30 Apr 2012. <http://www.ct.gov/dep/cwp/view.asp?a=2702&q=323482>.
- ↑ Wood, Stephen. "Section 8: The Good, The Bad, And The Ugly." Connecticut Museum Quest. N.p., 6 Oct 2007. Web. 18 Apr. 2012. <http://www.ctmuseumquest.com/?page_id=1055>.
- ↑ 12.0 12.1 12.2 12.3 12.4 Habitat type is categorized using the Habitats Classification Scheme (Version 3.0) defined by the International Union for Conservation of Nature and Natural Resources. <http://www.iucnredlist.org/technical-documents/classification-schemes/habitats-classification-scheme-ver3>.
- ↑ Teresa. "Prickly Pear Cactus." Eklund Native Species Garden. N.p., 26 May 2009. Web. 19 Apr 2012. <http://eklundgarden.blogspot.com/2009/05/prickly-pear-cactus.html>.
- ↑ "The Coastal Center at Milford Point." Connecticut Audubon Society. Connecticut Audubon Society, n.d. Web. 23 Apr 2012. <http://www.ctaudubon.org/coastal-center-at-milford-point/>.
- ↑ "History of the Park." West Rock Ridge Park Association. West Rock Ridge Park Association, n.d. Web. 7 May 2012. <http://westrockpark.wordpress.com/history/>.
- ↑ Emerson, George Barrell. A Report on the Trees and Shrubs Growing Naturally in the Forests of Massachusetts. 2. Boston: Dutton and Wenworth, State Printers, 1846. 424. Print. <http://books.google.com/books/reader?id=7c4VAAAAYAAJ&printsec=frontcover&output=reader>.
- ↑ "About West Rock." West Rock Ridge Park Association. West Rock Ridge Park Association, n.d. Web. 19 Apr 2012. <http://westrockpark.wordpress.com/about/>.
- ↑ "Foray." Mycological Society of America 2012 Meeting. Mycological Society of America, n.d. Web. 19 Apr 2012. <http://msa2012.net/schedule/fieldtrips.php>.
- ↑ Hornak, Michael. Blooming on the Fourth. 2011. Photograph. Flickr. Web. 1 May 2012. <http://www.flickr.com/photos/31522928@N08/5902419015/>.
- ↑ "Short Beach and Half Moon Cove 1946 to Present." The History of Lordship. N.p., n.d. Web. 16 May 2012. <http://www.lordshiphistory.com/ShortBeach2webpage.html>.
- ↑ Gamble, Ann. "Another go-round for Preserve." Shoreline Times n.d., n. pag. Web. 27 May. 2012. <http://www.shorelinetimes.com/articles/2010/12/28/news/doc4d1a676bbefcd804749323.txt?viewmode=fullstory>.
- ↑ Town of Old Saybrook. Old Saybrook Planning Commission. Planning Commission Minutes 1/5/2011. Old Saybrook: 2011. Web. <http://oldsaybrookct.virtualtownhall.net/pages/oldsaybrookct_pc/OldSaybrookCT_PCMinutes/2011/S02E0A808>.
- ↑ "Documents Relating To The Preserve". Alliance for Sound Area Planning. Alliance for Sound Area Planning, n.d. Web. 28 May 2012. <http://asap-ct.org/documents-relating-to-the-preserve/>.
- ↑ Colleran, Jim. "Westwood Trails, Guilford." A Walk Across the Giant: Day Hikes Around Connecticut. N.p., 26 Sep 2010. Web. 19 Apr 2012. <http://hikethegiant.blogspot.com/2010/09/westwood-trails-guilford.html>.
- ↑ "The Legend of Pleasure Beach." Bridgeport Library. Bridgeport Public Library, 9 Feb 2011. Web. 19 Apr 2012. <http://bportlibrary.org/hc/entertainment/the-legend-of-pleasure-beach/>.
- ↑ Feasibility Study and Master Plan for Pleasure Beach Park. City of Bridgeport, 2011. 37. Web. <http://www.scribd.com/doc/63235611/Pleasure-Beach-Planning-Bridgeport-CT-Community-Meeting-05-09-2011>.
- ↑ "Patrick Comins & the Important Bird Area at Long Beach West in Connecticut." BirdNote. BirdNote, n.d. Web. 19 Apr 2012. <http://www.birdnote.org/birdnote.cfm?id=1845>.
- ↑ Connecticut Wildlife. Jan/Feb 2003: 12. Print. <http://www.ct.gov/dep/lib/dep/wildlife/pdf_files/outreach/connecticut_wildlife_magazine/cwjf03.pdf>.
- ↑ "Forms and Schedules." Friends of Outer Island. Friends of Outer Island, 2012. Web. 29 May 2012. <http://www.friendsofouterisland.org/Page5.html>.
- ↑ "Russian Beach." Town of Stratford. Town of Stratford, n.d. Web. 19 Apr 2012. <http://www.townofstratford.com/content/1302/402/625/1100/5066/5107.aspx>
- ↑ "Russian Beach." Connecticut Coastal Access Guide. Connecticut Department of Energy and Environmental Protection, n.d. Web. 19 Apr 2012. <http://www.lisrc.uconn.edu/coastalaccess/sitemap.asp?siteid=339&act=1&mapaction=8&maptool=3>.
- ↑ State of Connecticut. Department of Environmental Protection, Office of Adjudications. Coastal Permit Application #200701968: Installation of a Pier, Ramp and Floating Dock, Town of Darien. Hartford: Connecticut Department of Energy and Environmental Protection, 2010. Web. <http://www.ct.gov/dep/lib/dep/adjudications/decisions_pdf/110910reynoldsproposedfinaldecision.pdf>.
- ↑ "The Nature Conservancy funds development of adaptive coastal restoration plan for Stratford Point ." Connecticut Audubon Society. Connecticut Audubon Society, 16 Jun 2011. Web. 19 Apr 2012. <http://ctaudubon.blogspot.com/2011/06/nature-conservancy-funds-development-of.html>.
- ↑ "Controlled burn at Stratford Point!" Connecticut Audubon Society. Connecticut Audubon Society, 2 Mar 2012. Web. 19 Apr 2012. <http://ctaudubon.blogspot.com/2012/03/controlled-burn-at-stratford-point.html>.
- ↑ 2008 Comprehensive Conservation and Management Plan Implementation Tracking Report. The Long Island Sound Study, 2010. 55. Web. <http://longislandsoundstudy.net/wp-content/uploads/2010/09/Combined-Document-2009-TMReport1.pdf>.
- ↑ The George Safford Torrey Herbarium. Department of Ecology and Evolutionary Biology, University of Connecticut, n.d. Web. 4 May 2012. <http://bgbaseserver.eeb.uconn.edu/database.html>.
- ↑ Prichard, Sarah Johnson. The Town and City of Waterbury, Connecticut. 1. Waterbury: The Price & Lee Company, 1896. 11. Print. <http://books.google.com/books?id=U_QLAAAAYAAJ&printsec=frontcover>
- ↑ 38.00 38.01 38.02 38.03 38.04 38.05 38.06 38.07 38.08 38.09 38.10 38.11 38.12 38.13 38.14 "YPM Botany - Online Catalog." Yale Peabody Museum of Natural History. Peabody Museum of Natural History, Yale University, n.d. Web. 16 May 2012. <http://peabody.yale.edu/collections/botany>.
- ↑ 39.0 39.1 39.2 39.3 39.4 39.5 Graves, Charles Burr. Catalogue of the Flowering Plants and Ferns of Connecticut Growing Without Cultivation. 14. State Geological and Natural History Survey, 1910. eBook. <http://books.google.com/books?id=SSQwAAAAYAAJ&printsec=frontcover#v=onepage&q=opuntia&f=false>.
- ↑ 40.00 40.01 40.02 40.03 40.04 40.05 40.06 40.07 40.08 40.09 40.10 40.11 40.12 The George Safford Torrey Herbarium (CONN). University of Connecticut, Department of Ecology and Evolutionary Biology, n.d. Web. 16 May 2012.
- ↑ "Connecticut Botanical Society." Consortium of Northeastern Herbaria. Consortium of Northeastern Herbaria, n.d. Web. 17 May 2012. <http://neherbaria.org/unitedstates>
- ↑ Riegel, Andrew. "Some Coactions of Rabbits and Rodents with Cactus." Transactions of the Kansas Academy of Science. 44. (1941): 96-103. Print. <http://www.jstor.org/stable/3624871>.
Other Useful Links[edit]
Connecticut Botanical Society
Prickly-pear (Opuntia humifusa)
Connecticut Museum Quest Section 8: The Good, The Bad, And The Ugly