Appearance
The overall form of "Opuntia engelmannii" is generally shrubby, with dense clumps up to 3.5 metres high, usually with no apparent trunk. The pads are green, obovate to round, about 15–30 cm long and 12–20 cm wide.The glochids are yellow initially, then brown with age. Spines are extremely variable, with anywhere from 1-8 per areole, and often absent from lower areoles; they are yellow to white, slightly flattened, and 1–6 cm long.
The flowers are yellow, occasionally reddish, 5–8 cm in diameter and about as long. Flowering is in April and May, with each bloom lasting only one day, opening at about 8AM and closing 8 hours later. Pollinators include solitary bees, such as the Antophoridae, and sap beetles.
The purple fleshy fruits are 3–7 cm long.
Naming
It goes by a variety of common names, including "cow's tongue cactus", "cow tongue prickly pear", "desert prickly pear", "discus prickly pear", "Engelmann's prickly pear", and "Texas prickly pear" in the US, and "nopal", "abrojo", "joconostle", and "vela de coyote" in Mexico.
Distribution
The "Opuntia engelmannii" range extends from California to Louisiana in the United States, and from Sonora to the Tamaulipan matorral in Chihuahua, 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.
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