Thistle Cholla

Small plants of Cylindropuntia tunicata arising from fallen fruits or seeds consist of series of subspheric segments resembling club-chollas; those have been named Opuntia stapeliae de Candolle (N. L. Britton and J. N. Rose 1919-1923, vol. 1). Apparently in some areas, few of these make it to maturity and larger young plants are rarely seen.

Shrubs, densely branched, 0.3-0.6 m. Stem segments easily detached, whorled or subwhorled, pale green to green, 5-20(-25) × 1.5-2.5 cm; tubercles very prominent, broad, 2-3 cm; areoles obdeltate, 4.5-8 × 2.5-5 mm; wool yellow-tan, aging gray. Spines 5-12 per areole, at most areoles, spreading, obscuring stems, yellow, acicular, larger ones 3-6 cm; sheaths persisting, yellow to tan, loosely fitting, 2-4 mm diam. Glochids in small adaxial tuft, pale yellow, 0.5-1.2 mm. Flowers: inner tepals yellow to yellow-green, spatulate, 15-20 mm, apiculate; filaments yellowish; anthers yellow; style green to reddish; stigma lobes yellow-green to green. Fruits usually sterile, not proliferating, yellow to yellow-green, often tinged red, top-shaped to clavate, 25-50 × 8-15 mm, pulpy, tuberculate, spineless or sometimes weakly spined; tubercles subequal; umbilicus 5-7 mm deep; areoles 32-40. Seeds light tan, ± obovate, to 2.5 × 2 mm; girdle smooth. 2n = 22.

Flowering late spring (May-Jun). Chihuahuan Desert, sandy to gravelly substrates, usually calcareous slopes or alluvium; 1500 m [2000-2300 m]; Tex.; Mexico; South America (Chile, Ecuador).

Cactus tunicatus Lehmann, Nova Acta Phys.-Med. Acad. Caes. Leop.-Carol. Nat. Cur. 16: 319. 1832; Opuntia tunicata (Lehmann) Pfeiffer

Cylindropuntia tunicata, commonly referred to as sheathed cholla, is a cholla native to the Chihuahuan Desert of North America and parts of South America.