Clokey, Madrono 7(3): 71, 1943
What is Opuntia charlestonensis?
Opuntia charlestonensis is a prickly pear cactus that occurs from about 6,000 to 8,000 ft on Mt Charleston, NV. It is proposed to be a hybrid cactus derived from two species, O. phaeacantha and O. polyacantha erinacea.
O. charlestonensis is sympatric with the two proposed parental Opuntias, but an O. dulcis-like Opuntia species also grows in Kyle canyon. This latter Opuntia has not been investigated as a possible parent.
Plants may be 20 to 40 cm tall and up to 1.5 m across. They are generally prostrate, but short branches of a few cladodes may arise from prostrate main branches. Cladodes are oval or obovate and 10-20 cm long and 7-14 cm wide. Cladodes may be strongly purple in the winter and spring. Spines (4-6) are light in color, and spreading in all directions.
O. charlestonensis has yellow or canary-yellow flowers that darken late on the day of anthesis; there may be a blush of red in the flower centers. Flowers are 4-5 cm across. Stamens and anthers are yellow as is the style and stigma. However, the style may be tinged with red. Fruit is oval and dull reddish-purple with a green pulp. Seeds are flat and 4-5 mm in diameter. Despite its pentaploid nature, it seems to reproduce locally, perhaps clonally.
This prickly pear was only known from Kyle Canyon on Mt. Charleston, NV. However, a 2014 record reported a population of this Opuntia in CA where it also seemed to be formed by hybridization. See the original description. O. charlestonensis is pentaploid.