Habit: Erect, branched [or not], forming compact, +- 1 m diam mounds; branches 30--50(130).
Stem: not segmented, [4]15--40[250] cm, [8]15--30[80] cm diam, flat-topped spheric to short-cylindric, hard, tip densely woolly [to glabrous]; ribs [7]11--25[60+], prominent, tubercles indistinct.
Spines: (5)10--19 per areole, generally 2--5 mm diam near base, generally awl-shaped, generally flat, ringed with conspicuous ridges, straight to curved; central spines [1]4 per areole.
Flower: at stem tip, near distal edge of spine cluster, 4--5 cm diam; perianth yellow tinged with pink; ovary densely long-woolly, spines 0, scaly, distal scales long-tapered, tips spine-like.
Fruit: dehiscent via basal pore, ovoid, densely woolly, spineless, but distal scales spine-like at tip.
Seed: 2.8--4.7 mm, spheric, or +- reniform to obovoid, shiny or dull, +- red-brown to black.
Species In Genus: 6 species: southwestern United States, Mexico.
Etymology: (Greek: spine + cactus)
Jepson eFlora Author: Bruce D. Parfitt
Reference: Chamberland 1997 Syst Bot 22:303--313
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
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