Mammillaria heyderi, a frost-tolerant species, is quite widespread across higher elevations of the Southwest deserts, from Arizona to Texas, usually between 3,000 and 6,000 feet elevation but extending all along the Rio Grande to near sea level by the Gulf of Mexico. The cactus has an unusual, compressed appearance, remaining nearly flat against the ground, instead growing outwards and downwards, but never becoming much more than six inches across.
The green stem bears prominent tubercles, each topped by 8 to 18 short, whitish (brown at the tip) spines which do not obscure the body of the plant; all are radials apart from one slightly longer central spine. This is the only Southwest cactus with milky sap.
Two varieties are currently recognized (bullingtoniana and heyderi), distinguished by spine characteristics.
Scientific name:
Mammillaria heyderi
Common name:
Heyder pincushion cactus, little nipple cactus, cream pincushion
Range:
Southeast Arizona, south New Mexico, west and south Texas (along the Rio Grande); also the Texas Panhandle and a small area of southwest Oklahoma
Form:
Flat, disc-shaped, solitary
Habitat:
Scrubland, grassland, pinyon-juniper foothills
Flowers:
Pink, yellow or cream, with a darker, yellow/brown stripe underneath
Distribution map for mammillaria heyderi
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