Hamatocactus bicolor

Description

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.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 EFloras.org.

Genus Hamatocactus

Plants erect , unbranched or branched in basal portion, not deep-seated in substrate. Roots diffuse . Stems unsegmented , bright deep green, hemispheric when young, becoming spheric or ovoid to cylindric , 3.6-12(-20) × 4.5-12 cm, glabrous ; ribs 13, spiraling or vertical , slender, crests sinuate , sharp, not interrupted or undulate , narrow; areoles circular or, on older parts of stem, elliptic to ovate , adaxially elongated into short areolar grooves ; areolar glands golden, darker with age, cylindric or peglike; cortex and pith firm, not mucilaginous . Spines 11-20 per areole, not obscuring stems, yellowish, whitish, or reddish brown, acicular (rarely central spine flattened), longest spines 12-38 mm; radial spines 10-19 per areole, straight or slightly curved toward stem, longest spines 11-32 mm; central spines 1 per areole, porrect , hooked , terete (rarely flattened). Flowers diurnal , near stem apex, at adaxial edge of areoles or at axillary ends of short areolar grooves, widely funnelform , 3.7-7 × 4-7 cm; outer tepals finely fringed ; inner tepals yellow (to ivory) with red bases , 20-25 × 6-9 mm, margins entire , toothed , or lacerate ; ovary scaly , hairless, spineless; stigma lobes 5-11, pale yellow to orangish, 3-7 mm. Fruits indehiscent or eventually dehiscent by vertical slits, bright red, spheric or nearly so, ca. 10 × 8-13 mm, fleshy , with 15 or fewer whitish, broad fringed, naked, spineless scales ; floral remnant persistent . Seeds black, obovoid , usually 1-1.4 × 0.8-1 mm, minutely papillate ; testa cells weakly convex , nearly flat toward proximal end of seed. x = 11.

Species 1: arid regions, sw United States, Mexico.

Hamatocactus has been submerged in Ferocactus or Thelocactus by various authors and grouped with Glandulicactus by others.Allan D. Zimmerman & Bruce D. Parfitt "Hamatocactus". in Flora of North America Vol. 4 Page 98, 207, 208, 218. Oxford University Press. Online at EFloras.org.

Taxonomy

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Domain: Eukaryota () - Whittaker & Margulis,1978
- Kingdom: Plantae () - Haeckel, 1866 - Plants
  - Subkingdom: Viridaeplantae () - Cavalier-Smith, 1981
    - Phylum: Magnoliophyta () - Sinnott, 1935 Ex Cavalier-Smith, 1998 - Flowering Plants
      - Subphylum: Euphyllophytina ()
        Infraphylum: Radiatopses () - Kenrick & Crane, 1997
        Class: Magnoliopsida () - Brongniart, 1843 - Dicotyledons
        Subclass: Caryophyllidae () - Takhtajan, 1967
        Superorder: Caryophyllanae () - Takhtajan, 1967
        Order: Caryophyllales () - Perleb, 1826
        Suborder: Portulacineae ()
        Family: Cactaceae () - Durande, 1782, Nom. Cons. - Cactus Family
        Genus: Hamatocactus () - Britton & Rose, Cact. 3: 104, figs. 110-114. 1922. - Twisted-rib cactus [Latin hamatus, hooked, in reference to the hooked central spines, and Cactus, an old genus name]
        Specific epithet: bicolor - I.M.Johnst.
        Botanical name: - Hamatocactus bicolor I.M.Johnst.