Pediocactus simpsonii

(Mountain Cactus)


Pediocactus simpsonii, Troublesome Creek Area, Grand Co. 2217

Scientific Name Pediocactus simpsonii USDA PLANTS Symbol PESI
Common Name Mountain Cactus, Simpson Hedgehog Cactus ITIS Taxonomic Serial No. 19776
Family Cactaceae (Cactus) SEINet
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Description Life zones and habitat: Foothills and montane (5200 to 10500 ft.); dry soils on rocky hillsides.
Plant: Small, often solitary cactus plants with spherical or ovoid stems that may be flattened or depressed; 1 to 6 inches across.
Pads & Spines: No pads; stems are green with short conical tubercules, almost obscured by spines, each with an areole at the top; 15 to 35 white widely spreading radial spines, 0.1 to 0.5-inch long; 4 to 11 central spines per areole, reddish brown with lower half cream or yellow, 0.2 to 0.8 inches long.
Inflorescence: Flowers are up to 1 inch across with usually pink tepals, but may be white, cream, yellow or magenta; stamens are yellow and stigma lobes green.
Bloom Period: April to June.
Fruit: Short cylindrical, green tinged with red or turning reddish-brown, less than 1/2-inch long.
References: "Flora of Colorado" by Jennifer Ackerfield, iNaturalist and SEINet.
Note: Pediocactus simpsonii has adapted to survive in cold and dry environments and can be found at higher elevations than any other cactus in North America.
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Colorado Status:

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