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24. Colocasia Schott in Schott & Endlicher, Melet. Bot. 18. 1832.
芋属 yu shu
Authors: Heng Li & Peter C. Boyce
Leucocasia Schott.
Herbs, seasonally dormant or evergreen, small, medium sized, or gigantic, latex-bearing. Stem either a hypogeal, subglobose or subcylindric tuber or mostly epigeal, massive. Leaves several, rosulate in acaulescent plants, forming a terminal crown in arborescent species. Petiole glabrous, sometimes strikingly glaucous, rarely pubescent, sheath rather long; leaf blade peltate, ovate-cordate to sagittate-cordate, abaxially glabrous, glaucous, pruinose, rarely pilose; posterior lobes rounded, shortly to almost entirely connate; basal ribs well developed, primary lateral veins pinnate, forming submarginal collective vein, 1 or 2 marginal veins also present, secondary and tertiary laterals arising from primaries at a wide angle, then arching strongly toward leaf margin and forming inconspicuous interprimary collective veins, higher order venation reticulate. Inflorescences 1 to many per each floral sympodium, appearing with leaves; peduncle mostly shorter than petioles. Spathe constricted between tube and limb, sometimes with a second weaker constriction above male zone of spadix; tube persistent, enlarging in fruit and then splitting open irregularly from apex, with convolute margins, usually much shorter than limb, ovoid or oblong; limb either remaining erect, and ± furled, or opening and then reflexed at anthesis, later deciduous, white or yellow, very narrowly lanceolate to oblong or boat-shaped. Spadix sessile, shorter than spathe; female zone short, separated from male by narrower zone of sterile male flowers or contiguous with male zone; male zone cylindric to fusiform; terminal appendix erect, ± smooth, narrowly conic to fusiform or subulate, sometimes reduced to a small, mucronate stub, or absent. Flowers unisexual, naked. Ovary ovoid or oblong, 1-loculed; ovules many, hemiorthotropous; funicles relatively long; placentae 2-5, parietal; stylar region short, narrowed or not, sometimes ± absent; stigma disciform-capitate or weakly lobed. Interpistillar staminodes present in some species, these weakly clavate, equaling associated pistil; interfloral synandrodes (where present) depressed obpyramidal, laterally compressed, truncate. Male flowers 3-6-androus; stamens connate into ± truncate synandrium; thecae lateral, oblong-linear, dehiscing by apical pore. Infructescence erect or declined by flexing of peduncle. Fruit a greenish to whitish or dull orange, obconic or oblong, strongly fruit-smelling berry, many seeded; stigma remnants persistent. Seed tiny, ovoid to ellipsoid; testa thickish, costate; embryo axile, cylindric; endosperm copious.
About 20 species: tropical and subtropical Asia; six species in China.
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1 |
Petioles and peduncle pubescent; leaf blade abaxially pilose. |
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1 C. menglaensis |
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Plants glabrous |
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(2) |
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2 (1) |
Plants gigantic, often exceeding 2 m tall; petioles and abaxial surface of leaves white pruinose; inflorescence arising as a fan of 5-13 inflorescences; spathe limb pure white. |
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2 C. gigantea |
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Plants small to large (very rarely exceeding 1.5 m tall); petioles and abaxial surface of leaves at most grayish glaucous; inflorescence solitary or in pairs, rarely 4 together and then not in a fan; spathe limb not pure white |
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(3) |
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3 (2) |
Plants large, with tuberous, rhizomatous, or stoloniferous stems; spathes yellow |
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(4) |
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Plants small, stoloniferous; spathes pale green or somewhat purplish or purplish brown |
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(5) |
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4 (3) |
Leaf blade adaxially matte waxy-glaucous and water-shedding (water sometimes forming "mercury droplets"); spathe limb dull yellow, opening only at base slightly above constriction, remainder staying furled; infructescence declined. |
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3 C. esculenta |
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Leaf blade adaxially glossy and wettable (water forming an even coating); spathe limb bright yellow, spreading and opening flat; infructescence erect. |
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4 C. antiquorum |
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5 (3) |
Stolons very slender, much branched; leaves frequently with dark patches between primary lateral veins; female and male zones contiguous. |
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5 C. affinis |
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Stolons robust, little branched; leaves usually concolorous green; female and male zones separated by a zone of synandrodes. |
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6 C. fallax |
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Lower Taxa
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