Siler Pincushion Cactus

Sun Exposure: Full sun

Origin: USA (southwestern Utah and northwestern Arizona), where it is restricted to a specific gypsum and salt-rich soil, from 3000 to 5500 feet elevation (900 to 1650 m)

Growth Habits: Solitary, occasionally clustered globose cactus, stems typically 4 inches tall (10 cm), but can reach up to 18 inches tall (45 cm), 3 to 4 inches in diameter); 3 to 7 brown central spines becoming white with age, 1 inch long (2.5 cm); 11 to 16 whitish radials.

Potential threats include off-road vehicle traffic, and trampling by livestock, especially in wet soils. Gypsum mining is no longer considered a threat since the gypsum in P. sileri habitat is of low quality and quantity (source U.S. Fish and Wildlife Service).
The species was described based on specimens collected by A.L. Siler in May of 1883 at Cottonwood Springs and Pipe Springs. The species epithet was named after him.

Blooming Habits:
Yellow flowers with purple veins, 1 inch in diameter (2.5 cm) during March and April.

Culture:
Can probably use some added gypsum in the soil mixture.