Family: Cactaceae |
Plants treelike or shrubby, erect to trailing, usually with many branches, sometimes forming clumps or mats; trunks when present, initially segmented, appearing continuous with age; main axes determinate, usually terete. Stem segments 2-60(-120) cm long, 1.2-40 cm, wide, usually flattened, circular, elliptic, ovate, lanceolate, or obovate to oblanceolate, green or sometimes reddish to purple, nearly smooth to tuberculate, glabrous or pubescent; areoles 3-8(-10) mm long, 1-7(-10) mm wide, usually elliptic, circular, or obovate; wool white, gray, or tan to brown, aging white or gray to black; spines 0-15+ per areole, to 75(-170) mm long, white, yellow to brown, red-brown to gray, or black, sometimes partly to wholly white chalky (chalkiness disappearing when wet), aging gray to dark brown to black, with epidermis intact, not sheathed, acicular to subulate, sometimes setose or with hairlike bristles, terete to angular-flattened, tips sometimes paler or yellow; glochids in adaxial crescent at margin of areole, in tuft or encircling areole margin, white to yellow to brown, or red-brown, aging white to brown or red-brown. Flowers usually bisexual, sometimes functionally staminate, radially symmetric; outer tepals green to yellow with margins tinged with color of inner tepals; inner tepals pale yellow to orange, pink to red or magenta, rarely white (unicolored) or with base of a different color (bicolored), oblong to spatulate, emarginate-apiculate; nectar chambers simple, open, not covered by proximal thickening styles. pollen yellow, grains reticulate or foveolate (opuntioid type). Fruits 10-120 mm long, 8-120 mm acorss, sometimes proliferating (sprouting from another fruit), if fleshy, green, yellow, or red to purple or, if dry, tan to gray, straight, sometimes stipitate, clavate to cylindric, ovoid, or obovoid to subspheric, fleshy to juicy or dry, smooth or tuberculate, spineless or spiny, sometimes burlike; seeds 2-7 mm long, 7-7 mm across, pale yellow to tan or gray, generally circular to reniform, flattened (discoid) to subspheric, angular to squarish, sometimes warped, glabrous, commonly bearing 1-4 large, shallow depressions due to pressures from adjacent developing seeds; girdle protruding 0.3-3.5 mm, forming a ridge or flat wing, or not protruding. Opuntia has about 150 species, all native to the Americas, Caribbean and Galapogos Islands. Many taxa are plants as ornamentals. for fences, food or animal fodder, ot to stabilize sand dunes. Some species are obnoxious weeds, aided by the ability of the stem segments to survive months without any moisture, even when separated from the parent plant, reviving and with the potential for establishment when conditions become favorable. |