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biznaga-tonelmancamula, devilshead, silverbell cactus, Turk's head cactus

biznaga-tonel manca caballo, devil's pincushion, horse crippler

Habit Plants normally unbranched. Plants unbranched (very rarely branched).
Stems

pale gray-green to bright gray-blue, flat-topped or hemispheric and deep-seated in sub-strate, spheric with age or stoutly short cylindric (remaining hemispheric at high elevations), 4–25(–45) × 8–15(–20) cm;

ribs (7–)8(–9), vertical to helically curving around stem, rib crests broadly rounded, uninterrupted or slightly constricted between areoles.

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

(5–)8(–10) per areole, loosely projecting or strongly decurved, pink, gray, tan, or brown, strongly annulate-ridged, subulate, ± flattened, glabrous, generally not hiding stem surface;

radial spines 5(–8) per areole, similar to central spines;

central spines 1(–3) per areole, 18–43 × 1–2.5(–3) mm, longest spine usually descending, straight or decurved throughout its length.

(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

5–7 × 5–6.5(–9.5) cm; inner tepals bright rose-pink or magenta, color ± uniform from base to apex, 3 × 1.5 cm, margins entire to serrate;

stigma lobes pinkish to olive.

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 or weakly dehiscent through basal abscission pore, pink or red, spheric to ovoid-cylindric, surfaces partly or entirely hidden by hairs from axils of scales and long areolar hairs of stem apex, usually quickly drying to tan shell before seed dispersal, 10–30 mm;

scales several, tips dark, spinelike, glabrous.

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 or gray, angular or slightly wrinkled, spheric to obovoid, 2–3 mm;

testa cell surfaces slightly convex, with weak network pattern of slightly protruding anticlinal cell walls.

black, spheric-reniform or irregularly obovoid, 2.5–3 mm, glossy;

testa cells flat or very slightly convex.

2n

= 22.

= 22.

Echinocactus horizonthalonius

Echinocactus texensis

Phenology Flowering Apr–Sep. Flowering late spring.
Habitat Arid rocky slopes, primarily limestone Chihuahuan Desert, grasslands, openings in oak woodlands, Tamaulipan thorn scrub, deep soils, saline flats, low limestone hills
Elevation 600-1700(-2500) m [2000-5600(-8200) ft] 0-1400 m [0-4600 ft]
Discussion

The Sonoran Desert populations of Echinocactus horizonthalonius have been segregated as var. nicholii, but are relatively similar to plants in New Mexico and extreme western Texas. Much greater morphologic diversity exists farther east and in Mexico, where shorter-spined, nearly flat-topped plants, which are more distinctive than the Sonoran Desert populations, have escaped taxonomic distinction.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Distribution
from FNA
AZ; NM; TX; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
NM; TX; Mexico (Coahuila, Durango, Nuevo León, Tamaulipas)
[WildflowerSearch map]
[BONAP county map]
Parent taxa Cactaceae > subfam. Cactoideae > Echinocactus Cactaceae > subfam. Cactoideae > Echinocactus
Sibling taxa
E. polycephalus, E. texensis
E. horizonthalonius, E. polycephalus
Synonyms E. horizonthalonius var. nicholii Homalocephala texensis
Name authority Lemaire: Cact. Gen. Sp. Nov., 19. (1839) Hopffer: Allg. Gartenzeitung 10: 297. (1842)
Source Flora of North America vol. 4, p. 189. Flora of North America vol. 4, p. 190.
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