Tuesday, May 11, 2010

Prickly Pear

DSCN1472 Often prostrate and fairly unremarkable in the landscape (unless you sit on one), the prickly pear cactus (Opuntia humifusa) can be a real show stopper when in bloom. Dazzling yellow blossoms, open only during the day, festoon these bristly herbs in the warm spring and summer months.

DSCN1448 The pads of the prickly pear are actually the stems of the plant. The leaves have been reduced to spines. Spines come in two forms; notable stiff spines about an inch in length and the less noticeable  fine tufts of short spines (glochids) that can stick and stay anywhere you come in contact with them (ouch).

cochineal Often in the fall you will come across a prickly pear in the Back Woods that appears to be covered in a white cottony material. The white cottony (actually waxy) mass is providing cover for the cochineal scale insect. An extract (the red goo on my finger) from this  insect has been used as textile dye for centuries and is even used as a food grade colorant today (look closely at the label on your red grapefruit juice.) There are some nice details from this UCLA site about the cochineal scale and its uses.

Prickly pear fruit (tunas) as well as the pads (nopales) are edible to humans and wildlife. The pads, fruit and seeds are an important food resource for our gopher tortoise population as well as for our songbirds, woodpeckers, and small mammals. Be sure to peel the fruit carefully before grazing in the field…the fruit are also dotted with those fine tufts  of spines!

There are  six species of native prickly pear cactus in Florida, two of which are endangered and one is threatened (our Opuntia humifusa has a stable population for now.) Habitat destruction is the primary cause of decline for many of these species but, all prickly pear have been further threatened by introduced insect species. Several non native moths ,most notably the  cactoblastis moth (Cactoblastis cactorum), were introduced to the state and their caterpillars have adversely affected our native, endemic, threatened, and endangered prickly pear cactus species. Current efforts to control the cactoblastis moth include removing infected plants and the release of sterile moths to reduce and contain the infestation in the southeast. It is hoped these measures will prevent the spread of the moth westward in the U.S. and to Mexico where Opuntia species are important agricultural crops not only for livestock but for humans as well.

Look for this interesting plant in the high, dry, open and sandy areas of the Back Woods primarily in the eastern and western sandhills.


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