Echinocactus polycephalus
Cactaceae subfam. cactoideae
cotton top cactus, many-head barrel cactus
diffuse, taproots, or tuberlike, sometimes adventitous.
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.
segmented or unsegmented, usually conspicuously succulent with thick cortex and pith, surface usually ribbed or tuberculate, usually somewhat woody with wood confined to internal ring, bark sometimes becoming proximally hardened and woodlike;
areoles circular to linear [protracted into finger-shaped shoots in Neoraimondia of South America], hourglass-shaped in some genera, with spiny portion separated from flowering portion by a groove in the stem surface, spiny areoles completely separate from flowering areoles in some genera, bearing 0–90 spines, glochids absent.
absent or rudimentary and microscopic or nearly so, less than 1 mm.
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.
acicular, subulate, daggerlike, ribbonlike, hairlike, or bristlelike, smooth, rough, striate, or annulate-ridged, glabrous (rarely pubescent), epidermis intact, not separating as sheath.
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.
diurnal to nocturnal, bisexual (rarely unisexual or functionally so), solitary in areoles (rarely several), radially symmetric (rarely bilateral), sessile, broadly salverform, urceolate, funnelform, or long tubular;
flower tube epigynous, usually conspicuous, adnate to upward extension of stem surrounding ovary, 0.2–15[–30] cm;
triangular leaflike bracts or small scales sometimes present on ovary and flower tube;
nectary often apparent, forming open chamber surrounding base of style.
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.
dehiscent or indehiscent, depressed-spheric or spheric to long clavate, juicy, fleshy, or dry;
perianth persistent or deciduous.
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.
1–3000+, yellowish, reddish, brown, or black, spheric, comma-shaped, lenticular-reniform, pyriform, or obovoid, 0.4–5 mm, rarely strophiolate, never arillate.
Echinocactus polycephalus
Cactaceae subfam. cactoideae
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.)
Genera ca. 111, species ca. 1500 (28 genera, 121 species in the flora).
Subfamily Cactoideae is the most diverse group of the Cactaceae, in terms of size, architecture, habitat, and habit. The vast majority of North American species are xerophytic, with columnar to spheric or barrel-shaped stems. A few are geophytic, that is, stems are mostly deep-seated in the soil substrate, often with the plant consisting mostly of an enlarged taproot and the visible parts of the stems appearing nearly flush with the soil surface or nearly buried during drought, becoming taller and slightly more conspicuous only during the growing season. Fewer species still, are epiphytic, and those only in the tropical and subtropical regions of North America and South America.
In the following treatments, most authors have attempted to recognize varieties wherever current evidence is compelling. Where evidence is equivocal, our tendency has been to include greater variability within varieties and, hence, fewer formal trinomials. Unfortunately, in the absence of strong supporting evidence, herbarium specimens of cacti are usually inadequate for the purpose of making taxonomic decisions. As a consequence, some populations of conservation interest here have been placed into synonmy before critical studies have been conducted to determine quantitatively and objectively how distinct each population is, or which deserve varietal status. Authors do not intend to imply that other varieties should not eventually be recognized. More systematic work, including DNA research and field research of all variants, is needed as a prelude to reassessing the status of currently listed and proposed populations. Such populations need to be protected during the entire phase of analysis and reassessment.
(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
