Horse-crippler, devil’s-head, manca caballo

Homalocephala texensis (Hopffer) Britton & Rose

Plants unbranched (very rarely branched). Stems pale gray-green (desert populations) to grass green (eastern populations), above-ground portion flat-topped, hemispheric in old age but usually deep-seated, flush with soil surface, 10-30 × 10-30 cm; ribs 13-27, very prominent, straight, vertical, or sinuous on desiccated plants, crests ± sharp, without depressions between areoles but sometimes areoles recessed part way into rib. Spines (6-)7-8 per areole, mostly decurved or 1 porrect and straight, pale tan, pink, reddish to gray, terete to flattened, annulate, not hiding stem surfaces, minutely canescent with laterally compressed unicellular trichomes; radial spines (5-)6-7 per areole; central spine 1 per areole, porrect or descending, straight or distally decurved, (20-)40-60(-80) × 1.5-4(-8) mm. Flowers 5-6 × 5-6 cm; inner tepals bright rose-pink to pale silvery-pink, proximally orange to red, (15-)28-32 × (3-)6(-9) mm, margins usually erose; stigma lobes pink to pinkish white. Fruits indehiscent (rarely rupturing irregularly), scarlet or crimson, spheric to ovoid, 15-50 × 15-40 mm, fleshy, surfaces not hidden by widely spaced hairs in axils of scales; scales 13-21, distal scales spine-tipped, minutely puberulent. Seeds black, spheric-reniform or irregularly obovoid, 2.5-3 mm, glossy; testa cells flat or very slightly convex. 2n = 22.

Flowering late spring. Chihuahuan Desert, grasslands, openings in oak woodlands, Tamaulipan thorn scrub, deep soils, saline flats, low limestone hills; 0-1400 m; N.Mex., Tex.; Mexico (Coahuila, Durango, Nuevo León, Tamaulipas).

The western, desert populations of Echinocactus texensis, unlike the eastern plants, have longer central spines that project stiffly outward and can flatten off-road vehicle tires or seriously injure a large mammal stepping on them. A dense cover of ephemeral herbs or shallow blanket of snow can hide this species completely from view.