Editing Eastern Prickly Pear (section)

==== Gauging Severity of Etiolation ====

[[File:Opuntia-unusual-cladodes-1.jpg|thumb|right|Despite receiving several hours of direct sunlight each day, this cactus of the Long Beach Complex in Stratford, CT exhibits peculiarly elongated cladodes.  This unusual morphology is ''not'' caused by etoliation, but must represent some other genetic or environmental influence.]]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:

<ul>
<li>'''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.</li>
<li>'''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.</li>
</ul>

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.