2. Grusonia grahamii (Engelmann) H. Robinson, Phytologia. 26: 176. 1973.
Opuntia grahamii Engelmann, Proc. Amer. Acad. Arts 3: 304. 1856 (as grahami); Corynopuntia grahamii (Engelmann) F. M. Knuth; O. schottii Engelmann var. grahamii (Engelmann) L. D. Benson
Shrubs, forming mats, 8-20 cm. Roots tuberlike, 9 × 2 cm. Stem segments cylindric, curved and narrowed at base, 3-7 × 1.5-3.5 cm; tubercles narrow, 10-15 mm; areoles 3 mm in diam.; wool white to yellowish. Spines (6-)8-15 per areole, mostly in distal areoles, white, yellow, tan, or red-brown, longest 3-5.5 cm; major 2-3 abaxial spines erect and red-brown, marginal spines deflexed and whitened, angular-flattened to subterete; longest central abaxial spine usually brownish, with whitish wavy lines, usually straight; major 2-5 adaxial spines divergent, ascending, rich red-brown, ± terete. Glochids increasing in number toward base of stem segments, adaxial in areole, white to yellow, to 6 mm. Flowers: inner tepals bright yellow, 20-25 mm; filaments yellow-green; style and stigma lobes cream. Fruits yellowish, cylindric to ellipsoid, 20-35 × 12-20 mm, fleshy, spineless, yellow glochidiate; areoles 35-45. Seeds yellow, 4-5 × 3-4 mm, smooth (or with 1-2 broad bumps per side). 2n = 44.
Flowering late spring (May-Jun). Chihuahuan Desert, sandy, gravelly bajadas and flats; 700-1500 m; N.Mex., Tex.; Mexico (Chihuahua, Durango).