Engelmann & Bigelow, Proceedings of the American Academy of Arts and Sciences 3: 291, 1856
Opuntia chlorotica chlorotica is one of three varieties: chlorotica, santa-rita, and gosseliniana within the O. chlorotica complex as described by Ferguson (1988). O. chlorotica chlorotica is the prickly pear cactus that summons up visions of gunfights and posses. The Flora of North America online provides a technical description of this O. chlorotica variety. Plants may reach 2(2.5) m tall and usually from a single trunk that can reach 20 to 30 cm in diameter. Plants are often upright, but some spreading may occur. Cladodes are suborbicular or orbicular and may be about 12(20) cm across all diameters. Spines (2 to 3.5 cm long) are yellow and glochids can become prominent and robust on older pads, up to nearly 2 cm long. The trunk is spiny. Though most plants are have spiny pads, some populations are almost spineless (as near Congress, AZ). There may be 1 to 6 spines per areole that often bend back towards the cladode surface. See the original original description. The fruit pulp of this Opuntia is often colorless and without flavor. O. chlorotica is diploid.
An early photograph of O. chlorotica chlorotica (Bulletin of the Torrey Botanical Club, 1916) shows that this plant is distinctive. O. chlorotica chlorotica has spines on the trunk and pancake-like cladodes. Flowers are modest, about 2 inches across, and fruit is semi-spherical or egg shaped. O. chlorotica chlorotica is closely related to O. chlorotica gosseliniana and O. chlorotica santa-rita and the three Opuntias intergrade.
The plant is found in NV, CA, much of AZ, and barely into southwestern UT. It is also found in the extreme southwest of NM. Typically, O. chlorotica chlorotica grows in well-drained, rocky soils, sometimes between boulders or on cliff faces. However, this Opuntia species may grow in sandy soils as near Wikenberg, AZ.