Echinocactus polycephalus
Echinocactus horizonthalonius
cotton top cactus, many-head barrel cactus
biznaga-tonelmancamula, blue barrel cactus, devilshead, silverbell cactus, Turk's head cactus, visnaga meloncillo
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 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.
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.
(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.
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.
5–7 × 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.
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 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.
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 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.
= 22.
Echinocactus polycephalus
Echinocactus horizonthalonius
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 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.)
1. Scales of fruit 10-14 mm, reddish to maroon, aging tan to black, not protruding beyond dried perianth parts on fruit; seed papillate-roughened (exposed surfaces of testa cells protruding, hemispheric to hexagonally faceted, appearing dull except for the microscopically sparkling individual facets) | var. polycepha |
1. Scales of fruit 16-30 mm, reddish, tan, or yellow, aging yellow, usually protruding beyond dried perianth parts on fruit; seed smooth (exposed surfaces of testa cells flat or slightly convex, surfaces uniformly shiny) | var. xeranthem |
CalFlora
WildflowerSearch
iNaturalist
USDA Plants Database
