Engelman. Proceedings of the American Academy of Arts and Sciences 3: 297, 1856
Herbarium (possible lectotype); Herbarium (as O. nemoralis/macatee); Drawing (United States Pacific Railroad and Other Reports [USPRR] photographs/archival material (1825-185); plate XI, No. 4); 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 (see the drawing above. USPRR). 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.
One description is in the Cactaceae, v1, 1919 Britton and Rose, page 133.
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. nemoralis is a synonym of O. fusco-atra.
The color drawing is by Mary Emily Eaton, and may be from The Cactaceae, 1919. The plant depicted has flowers with red at the base of the inner tepals, a detail not mentioned in other work.
The following photographs represent our concept of O. fusco-atra based on the original description.