Plants unbranched or few branched, except in old age, ultimately forming mounds, rarely to 1 m diam., stems to 50, with most spines pressed against stem outline. Roots ± diffuse. Stems spheric to broadly short cylindric, 10-25(-30) × (7.5-)10-15 cm; tubercles 6-10 × 6 mm, firm; areolar glands seasonally conspicuous; pith 1/5 of lesser stem diam.; medullary vascular system conspicuous. Spines 12-20 per areole, tan or yellow, largest spines turning gray with red tips, all nearly terete; radial spines (12-)15-20 per areole, 12-15 mm, basally 0.5 mm diam.; central spines 1(-2) per areole, decurved, (15-)20 mm, usually less than 1 mm diam. Flowers distant from stem apex, forming ring around distal portion of stem, 25-40 × 25-40 mm; outer tepals denticulate; inner tepals 20-30 per flower, greenish yellow or lemon yellow, 18 × 3-4.5 mm; anthers pale yellow; stigma lobes ca. 5, pale green (requiring verification), ca. 2.5-2.8 mm. Fruits greenish white (drying yellow-green) to partly or wholly tinted with dull reddish brown, usually 1.5-2 times longer than thick, spheric or elongate, 9-12(-13) × (4-)5-7 mm, pulp sparse and soon drying; floral remnant strongly persistent. Seeds bright brown, spheric, finely and weakly raised-reticulate. Flowering summer; fruiting winter (Nov-Jan). Valleys, mesas, foothills, grasslands, oak belts, grassy or rocky areas; 1200-1800 m; Ariz.; Mexico (Sonora).