Engelman. Proceedings of the American Academy of Arts and Sciences 3: 297, 1856
Herbarium (as O. nemoralis/macatee); Drawing (Drawings/prints associated with USPRR reports & photographs/archival material; plate XI); Painting (Mary Emily Eaton)
What is Opuntia fusco-atra?
Little is known about this prickly pear. It is reported to grow west of Houston, Texas.
This Opuntia is purported to have stout brown, almost black, spines on small joints. The cladodes are 5-7 cm long and the spines are 2-3 cm long. The spines may be of two sizes with the lower one 1.5 cm long.
Flowers are yellow and about 3.5 cm in diameter. The ovary is 2.5 cm long and slender.
Ploidy is unknown.
Some botanists consider that O. fusco-atra is a form of O. nemoralis.