Opuntia phaeacantha be described as varieties or full species some day. Opuntia phaeacantha Opuntia phaeacantha is a species of prickly pear cactus known by the common names tulip prickly pear and desert prickly pear found across the southwestern United States, lower Great Plains, and northern Mexico. The plant forms dense but localized thickets. Several varieties of this particular species occur, and it also hybridizes easily with other prickly pears, making identification sometimes tricky. "Opuntia phaeacantha" has a characteristic prickly pear appearance, with flattened green pads bearing wool and spines. The spines are brown, reddish-brown, or gray, and often over 3 cm in
Opuntia engelmannii (state) to the Tamaulipan matorral in Chihuahua (state), in Mexico. In the Sonoran Desert, terminal pads face predominantly east-west, so as to maximize the absorption of solar radiation during summer rains. Although found occasionally in the Mojave Desert, it tends to be replaced by "Opuntia basilaris", which does not need the summer rain. The overall form of "Opuntia engelmannii" is generally shrubby, with dense clumps up to high, usually with no apparent trunk. The pads are green (rarely blue-green), obovate to round, about 15–30 cm long and 12–20 cm wide. The glochids are yellow initially, then brown with age. Spines