Editing Eastern Prickly Pear (section)

== Reproduction ==

''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.<ref name="us-forest-service">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>.</ref>

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.