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Echinocactus biceras


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Family Cactaceae

Fleshy perennials , shrubs , trees or vines , terrestrial or epiphytic. Stems jointed , terete , globose , flattened, or fluted , mostly leafless and variously spiny . Leaves alternate, flat or subulate to terete, vestigial, or entirely absent; spines, glochids (easily detached, small, bristlelike spines), and flowers always arising from cushionlike, axillary areoles (modified short shoots ) . Flowers solitary, sessile, rarely clustered and stalked (in Pereskia), bisexual , rarely unisexual , actinomorphic or occasionally zygomorphic. Receptacle tube (hypanthium or perianth tube) absent or short to elongate , naked or invested with leaflike bracts, scales , areoles, and hairs , bristles , or spines; perianth segments usually numerous , in a sepaloid to petaloid series. Stamens numerous, variously inserted in throat and tube; anthers 2-loculed, dehiscing longitudinally. Ovary (pericarpel) inferior, rarely superior, 1-loculed, with 3 to many parietal (rarely basal) placentas; ovules usually numerous; style 1; stigmas 2 to numerous, papillate , rarely 2-fid. Fruit juicy or dry, naked, scaly , hairy , bristly , or spiny, indehiscent or dehiscent , when juicy then pulp derived from often deliquescent funicles (except in Pereskia) . Seeds usually numerous, often arillate or strophiolate ; embryo curved or rarely straight; endosperm present or absent; cotyledons reduced or vestigial, rarely leaflike.

About 110 genera and more than 1000 species: temperate and tropical America; Rhipsalis baccifera (J. S. Mueller) Stearn native in tropical Africa, Madagascar, Comoros, Mascarenes, and Sri Lanka; some species of other genera now extensively naturalized in the Old World through human agency; more than 60 genera and 600 species cultivated as ornamentals or hedges in China, of which four genera and seven species more or less naturalized.[1]

Genus Echinocactus

Plants erect , branched or unbranched, forming compact mounds of 30+ branches, not deep-seated in substrate (or deep-seated in E. texensis and, if plants immature or at high altitude , in E. horizonthalonius). Roots diffuse or short taproots . Stems unsegmented , gray-blue, gray-green, yellow-green, or grass green, flat-topped spheric to short cylindric , 4-40(-45) [-250] × 8-30[-80] cm, apical region appearing copiously woolly (shortly velvety in E. texensis) [glabrous ]; ribs (7-) 8-27[-60+], very prominent , straight (or only slightly undulate ), sometimes helically curving around stems, broadly rounded to nearly keeled , rib crests uninterrupted or ± constricted between areoles; areoles widely spaced or confluent with age, nearly circular to oblong , with fertile portion as short, broad adaxial prolongation confluent with spine cluster ; areolar glands absent; cortex and pith hard, not mucilaginous . Spines (5-) 7-19 per areole, straw colored , pink, red, gray, tan, or brown, conspicuously annulate-ridged, rigid , stiff; radial spines 5-14 per areole, straight to curved , 2-5 cm; central spines 1-4 per areole, straight to curved, terete , flattened, or abaxially ridged . Flowers diurnal , near stem apex, near adaxial edges of short adaxial extensions of areoles, broadly funnelform to nearly salverform (more narrowly funnelform in E. texensis) ; outer tepals margins entire, apically spinose ; inner tepals yellow or pink to magenta, 2.4-3.2 × 0.3-1.5 cm, margins entire, serrate, toothed , or erose; ovary scaly , spineless, copiously woolly, with white or pale tan hairs from areoles hiding ovary and flower tube at anthesis ; scales 8-60, margins entire or fimbriate, spine-tipped; stigma lobes 6-14(-17), yellow, pink, or olive, 1-4.5 mm. Fruits either indehiscent or rupturing irregularly, or tardily dehiscent through basal abscission pore , whitish tan to pinkish (bright red in E. texensis), spheric to ovoid or ovoid-cylindric, 10-50 × 10-40[-100] mm, usually nearly dry (strongly succulent in E. texensis), many scaled ; axils of scales copiously woolly (wool hiding surface of fruits except in E. texensis), spineless, distal scales spine-tipped; pulp red; floral remnant persistent . Seeds reddish brown to black, spheric, or subreniform to obovoid , 2.4-4.7 mm, shiny or dull ; testa cells convex or flat. x = 11.

Species 6: sw United States, Mexico.

With the exception of the much-branched Echinocactus polycephalus, species of Echinocactus in the flora area are almost never branched, and will die instead of producing a lateral bud when the apex is injured. Smaller than normal fruits of Echinocactus are usually aborted and hollow as the result of infestation by insect larvae (M. Chamberland, pers. comm. ).[2]


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Similar Species

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Members of the genus Echinocactus

ZipcodeZoo has pages for 21 species, subspecies, varieties, forms, and cultivars in this genus:

E. cylindraceus (California Barrel Cactus) · E. emoryi (Emory's Barrel Cactus) · E. grusonii (Golden Barrel) · E. grusonii var. albispinus (Echinocactus) · E. horizontalonius (Devil's-Head Cactus) · E. horizonthalonius (Blue Barrel) · E. horizonthalonius Lem. var. horizonthalonius Lem. (Devilshead) · E. horizonthalonius Lem. var. nicholii L.Benson (Eagle Claw Cactus) · E. horizonthalonius var. horizonthalonius (Turkshead Barrel Cactus) · E. horizonthalonius var. nicholii (Arizona Turks Head) · E. ingens (Large Barrel Cactus) · E. macromeris (Nipple Beehive Cactus) · E. parryi (Echinocactus) · E. pectinatus (Rainbow Cactus) · E. platyacanthus (Biznaga Gigante) · E. polycephalus (Biznaga De Chilitos) · E. polycephalus Engelm. & Bigelow var. polycephalus Engelm. & Bigelow (Cottontop Cactus) · E. polycephalus xeranthemoides (Cottontop Cactus) · E. polycephalus var. polycephalus (Cottontop Barrel Cactus) · E. polycephalus var. xeranthemoides (Cottontop Cactus) · E. texensis (Candy Cactus)

More Info

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Further Reading

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  1. Zhen-yu Li & Nigel P. Taylor "Cactaceae". in Flora of China Vol. 13 Page 209. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at [back]
  2. Allan D. Zimmerman & Bruce D. Parfitt "Echinocactus". in Flora of North America Vol. 4 Page 97, 188, 207. Oxford University Press. Online at [back]
Last Revised: 2014-05-12