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Cottontop Cactus
Scientific Name: Echinocactus polycephalus Engelm. & J.M.Bigelow
Synonym: Emorycactus polycephalus
Family: Cactaceae

Show Larger Picture Echinocactus polycephalus at the Wallace's collection in Phoenix in April

Recommended Temperature Zone: sunset: 10-13 USDA: 8b-11 Frost Tolerance: Hardy to 10°F (-12°C) Minimum Avg. Temperature: 55°F (12°C) Sun Exposure: Full sun Origin: USA (Mohave and Sonoran desert: Arizona, California, Nevada), Mexico (northwestern Sonora) at low elevations Growth Habits: Clumping cactus, some colonies contains over 100 stems, spherical to short cylindrical stems, 12 to 24 inches tall (30-60 cm), 3.6 to 8 inches in diameter (9-20 cm); 12 to 18 ribs, 0.8 to 1.2 inches deep; large areoles, 0.4 inch in diameter (1 cm), 0.4 to 1.4 inches apart (1-3.5 cm); 4 central spines, 2 to 3.6 inches long (5-9 cm); 6 to 8 radials, 1 to 2 inches long (2.5-5 cm). Propagation: Seeds

Cultural Practices:
Yellow flowers, 2 to 2.4 inches long (5-6 cm), in February and March. The fruit is dry, covered with woolly hair, opening at the base when ripe, allowing the black seeds to escape.