Plants profusely branched, ultimately forming low mats or hemispheric mounds to 100 cm diam., immature branches sometimes predominant, conspicuously tuberculate with projecting spines. Roots ± succulent in largest, often massive and difficult to excavate. Stems deep-seated, aerial portion conspicuous, hemispheric to short cylindric, shape sometimes obscured by profusion of immature branches, 5-23 × (1.5-)4-8(-13.5) cm; tubercles unusually large, conspicuous, (10-)15-38(-45) × 6-15 mm, ± flaccid or flabby; areolar glands seasonally conspicuous; areolar grooves short, extending 1/2-3/4 distance from spines toward tubercle axils; parenchyma mucilaginous; pith narrow, ca. 1/10 of lesser stem diam.; medullary vascular system absent. Spines 7-21[-55] per areole; radial spines (3-)9-15(-18) per areole, white, gray, tan, or brown, (9-)16-25(-50) mm; subcentral spines 2-3 in adaxial part of areole; central spines (1-)3-8 per areole, (tan to) pale gray to black, abaxial central spine porrect or descending, others weakly appressed or ± projecting spines, slightly curved, usually angular in cross section (terete), sometimes flat and grooved on 1 side and rounded on the other, often slightly flexible, (15-)25-35(-55) mm, all equal or abaxial spine longest. Flowers apical or nearly so, 30-50(-60) × (30-)40-70 mm; outer tepals heavily fringed; inner tepals 20-25 per flower, bright rose-pink or magenta, often with darker midstripes and paler margins, 30-40 × 4.5-6 mm; outer filaments greenish white throughout or distally purplish pink; anthers bright yellow; stigma lobes 6-13, white or pale yellow, 3-6 mm. Fruits dark green, ovoid to obpyriform or ellipsoid, (10-)13-25(-30) × 12-18 mm; floral remnant strongly persistent. Seeds reddish brown, ± comma-shaped to spheric, 1.2-1.5 mm, finely and weakly raised-reticulate. 2n = 22.
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