Griffiths, Proceedings of the Biological Society of Washington 27(6): 27, 1914
Opuntia rugosa is a prickly pear cactus that was reported from Pomona, CA in the early 1900s and apparently never again. It is a low, ascending, and spreading cactus to about 20 to 30 cm tall. It is a about the size of O. camanchica; however, it may have branches that try to grow vertically for a few years. Plants often appear yellowish-green from a distance. The spines are white or yellowish, but may darken towards the base. Areoles may have 1 to 3 centrals up to 4 to 5 cm long. Shorter subsidiary spines may be recurved. The areoles are raised and give the pads a bumpy (rugose) look. The fruits are a little large for the size of the plant and the fruit is dark red-purple when ripe. Grown alongside other CA Opuntia species, the plants are distinct. This species may be limited to the immediate area of Pomona, CA near the Puddingstone Reservoir from where it was originally described, and if so, most of its range is covered in houses now. Status reports and population studies may be warranted for this Opuntia, and it is possible the species is essentially extinct. Its existence may be unknown to many California botanists because they may consider it to be the same as O. littoralis, O. vaseyi, O. semispinosa, O. phaeacantha, or even a hybrid due to L Benson’s treatment (The Cacti of the United States and Canada, 1982) of prickly pears. Benson treated many California opuntias hybrids. Remarkably, he proposed that some populations of cacti were hybrids with O. ficus-indica. See the original description.