Opuntia mojavensis

Opuntia mojavensis
Opuntia mojavensis

Engelmann & Bigelow, Proceedings of the American Academy of Arts and Sciences 3: 293, 1856

Lectotype; Herbarium (O. mojavensis-like); Herbarium (O. mojavensis-like); Herbarium (O. mojavensis-like); Drawing (The Botany of the Expedition, 1856)

What is Opuntia mojavensis?

Opuntia mojavensis is an enigmatic prickly pear cactus. The only  historical drawing of this cactus shows 2 spine clusters and an immature or sterile fruit. The herbarium sheet (lectotype) for this prickly pear also has limited material.

Details

O. mojavensis forms wood-stiff plants sprawling to 2 m across. In overall aspect, O. mojavensis resembles a double-sized O. phaeacantha but with distinctly angular branches caused by its woody nature. Cladodes are irregular in size and generally obovate. The spines seem similar to those of the lectotype as well as in the drawing above. However, spination is irregular and there are 0-2(5) spines per areole, even on the same pad. Plants may turn a pleasing red-purple color in winter. 

Flowers are 5-8 cm across and yellow with distinct red centers, green stigmas, and yellow anthers. Outer tepals are tinged with red or red-orange. Fruit is red (no purple) and may be barrel-shaped. 

We observed a population of plants growing at the summit of Mt Potosi (Highway 160 summit) near Las Vegas, Nevada that we interpret be O. mojavensis. We base our description on that population, and the photographs presented here show plants from that population. The original location (mountains above Victorville, CA) matches the Mt Potosi location in general terms of plant companions and altitude but is about 150 miles west of Mt. Potosi. Thus, we envision O.  mojavensis as a species of high elevations west of Arizona and across the Mojave Desert. More study is needed. See the original description. Ploidy is unknown. 

Because of its attractive  flowers, angular growth shape, and cold hardiness, O. mojavensis would be interesting in a garden. However, it is a large sprawling plant. 

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