Shrubs or small trees, erect, 0.6-2.5 m. Stem segments easily detached, whorled or sub-whorled, green-gray, 4-15 × 3.5-5 cm; tubercles prominent, broadly oval, 1.5-2.5 cm; areoles subcircular to obovate, 4-7 × 3-5 mm; wool tan, aging brown to black. Spines 6-12 per areole, in all but proximalmost areoles, spreading, usually deflexed in abaxial ones, pale red-brown to dark brown, acicular, the longest to 2 cm; sheaths pale yellow-brown, shiny. Glochids in adaxial crescent and few along margin of areole, yellow to brown, 0.5-2.5 mm. Flowers: inner tepals rose to magenta, to 20 mm; filaments yellow-green to distally tinted pink to magenta; anthers yellow, sometimes bearing stigma-tipped, stylelike appendages; style greenish yellow to often pink distally; stigma lobes yellow to white. Fruits usually sterile, often proliferating into short erect chains of 2-5 fruits, green, broadly ovoid to top-shaped, 21-25(-35) × 20-32 mm, fleshy, smooth to shallowly tuberculate, spineless; umbilicus broadly shallow, 5-7 mm deep; areoles (20-)25-35. Seeds rare, globose; girdle smooth. 2n = 22, usually 33.
Flowering spring (Apr-Jul). Ocean bluffs, inland coastal sage flats, hills; to 300 m; Calif.; Mexico (Baja California).
Cylindropuntia prolifera is of hybrid origin; it occupies a habitat different from its putative parents, C. alcahes (F. A. C. Weber) F. M. Knuth and C. cholla (F. A. C. Weber) F. M. Knuth, two Mexican species.