Echinocactus polycephalus |
Echinocactus texensis |
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cotton top cactus, many-head barrel cactus |
biznaga-tonel manca caballo, devil's pincushion, devil's-head, horse-crippler, manca caballo |
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Habit | Plants branched from base (rarely unbranched) forming compact mounds of 2–50(–130) branches. | Plants unbranched (very rarely branched). | ||||
Stems | gray-green to yellow-green, spheric to short cylindric, 15–40 × (9–)15–30 cm; ribs 11–25, usually vertical, or somewhat helically curving around stem, rib crests not constricted between areoles (slightly so when desiccated), sharp, with flat sides. |
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. |
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Spines | 10–19 per areole, straight to curved but not hooked, often twisted, red to straw colored, aging gray, flattened to abaxially ridged, annulate-ridged, nearly obscuring stem surfaces, glabrous to canescent with minute, white, unicellular trichomes often obscuring underlying spine color; radial spines 6–14 per areole; central spines 4, abaxial frequently longest, straight to somewhat recurved. |
(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. |
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Flowers | 5.5–5.8 × 4–6 cm, narrower when spines restrict flower from opening fully; inner tepals bright yellow, color uniform from base to apex, 24–26 mm, sparsely, minutely toothed; stigma lobes bright yellow. |
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. |
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Fruits | dehiscent through basal abscission pore, ovoid, surfaces largely hidden by hairs in axils of scales and long areolar trichomes of stem apex, usually drying to tan shell before seed dispersal, 15–40 mm; scales abundant, yellow to reddish throughout, or yellow with reddish midstripes, flat, tips spinelike, glabrous or canescent. |
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. |
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Seeds | dark maroon to black, ± obovoid-reniform or comma-shaped, 2.4–4.7 mm, smooth and shiny or granular and dull from protruding surfaces of testa cells; testa cell surfaces sometimes hemispheric to hexagonally faceted. |
black, spheric-reniform or irregularly obovoid, 2.5–3 mm, glossy; testa cells flat or very slightly convex. |
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2n | = 22. |
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Echinocactus polycephalus |
Echinocactus texensis |
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Phenology | Flowering late spring. | |||||
Habitat | Chihuahuan Desert, grasslands, openings in oak woodlands, Tamaulipan thorn scrub, deep soils, saline flats, low limestone hills | |||||
Elevation | 0-1400 m (0-4600 ft) | |||||
Distribution |
AZ; CA; NV; Mexico
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NM; TX; Mexico (Coahuila, Durango, Nuevo León, Tamaulipas)
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Discussion | Varieties 2 (2 in the flora). The varieties of Echinocactus polycephalus are distinguishable by several morphologic characteristics. Plants morphologically intermediate between the two varieties, however, occur at one site south of Lake Mead, Arizona, where the geographic ranges of the varieties are contiguous, but ecologically segregated. Although Echinocactus polycephalus var. polycephalus and var. xeranthemoides have been reported for southern Utah (L. D. Benson 1982; D. J. Ferguson 1992; G. Unger 1992), M. Chamberland (1995, 1997) found neither populations nor herbarium specimens from the past 100 years. (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.) |
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Key |
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Source | FNA vol. 4, p. 189. | FNA vol. 4, p. 190. | ||||
Parent taxa | Cactaceae > subfam. Cactoideae > Echinocactus | Cactaceae > subfam. Cactoideae > Echinocactus | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Homalocephala texensis | |||||
Name authority | Engelmann & J. M. Bigelow: Proc. Amer. Acad. Arts 3: 276. (1856) | Hopffer: Allg. Gartenzeitung 10: 297. (1842) | ||||
Web links |