Dioscorea polystachya

Dioscoreaceae

Dioscorea batatas Decne.

2. Dioscorea batatas Decne. in Rev. Hort. Ser. 4, 3:243. 1854; Bentham, Fl. Hongkong 368. 1861; Prain & Burkill in Journ. Asiat. Soc. Bengal n.s. 10:27. 1914; Knuth in Engl. Pflanzenr. 87(4-43):261,f.55. 1924; Sasaki, List Pl. Form. 113. 1928; Hand.-Mazz., Symb. Sin. 7:1240. 1936; Nemoto, Fl. Jap. Suppl. 1083. 1936; Prain & Burkill, Ann. Bot. Gard. Callcutta 14(2):243. 1939; Ohwi, Fl. Jap. 314. 1965; Liu, T. S. & T. C. Huang in Bot. Bull. Acad. Sin. 3(2):142. 1962; Liu, T. S. & T. C. Huang in Fl. Taiwan 5:101. 1978.

BY:Liao chunkuei

HABIT　DESCRIBE

　A glabrous, scandent vine from annual tuber; underground tuber cylindrical, growing down vertically to 1m long; epidermis greyish or brown; flesh white, edible, never poisonous; aerial stems annual, dextrorse, terete, herbaceous, ridged, green or violet; axillary aerial tubers globose and somewhat irregular branched, 5-15 mm long, 5-10 mm in diameter, greyish, glabrous, with reticulate lines and warts on surface. Leaves opposite or alternate near the base of stem, occasionally whorled, thick chartaceous, ovate-triangular, 3-10(16) cm long, 4-6(14) wide, 3-lobed, acuminate at apex, cordat or hastate or auricalate at base, warped inward, glabrous, green on both surfaces; nerves 7-9, concave at upper surface and convex at lower surface; petioles violet, 1.5-2 cm long, 2-3 mm thick, twisted and dilated at base, sulcate above.

　Staminate inflorescence axillary, spicate, 1-3 together; spikes with 25 flowers, 2-3 cm long; rachis zigzag, greenish, rigid. Male flowers alternate on rachis, globose, 1.5-2 mm in diameter, 2-bracted; outer bract widely ovate, ca. 2.2 mm long, ca. 1.1 mm wide, acuminate at apex; inner bract widely depressed ovate, ca. 1.5 mm long, ca. 1.2 mm wide, acute at apex, round at base; perianths 6, yellow-green with black- brown short-line spots; outer 3 perianths ovate, ca. 1.7 mm long, ca. 1.1 mm wide, obtuse at apex; inner 3 perianths ovate, ca. 1.5 mm long, ca. 1.2 mm wide, acute and thickened at apex; stamens 6, subequal; filament ca. 1.2 mm long, terete; anthers oblong, ca. 0.8 mm long, ca. 0.4 mm wide, dorsifixed, longitudinally dehiscent; pistillodium rudimentary, conicus, ca. 0.5 mm tall; stigmatiform 3-lobed. Pistillate inflorescence spicate, axillary, pendulous. Fruit capsulate, pendulous, tripterous. Seeds orbicular, broadly membranously winged around.

This introduced species has been cultivated for a long time. It has never been collected in the field of Taiwan.

The species is flowering from June to September, fruiting from July to November.

SPECIMENS EXAMINED

SPECIMENS EXAMINED. Kaohsiung Hsien: K’ao-t’an (Fenshan-shih) , C. K. Liao 990,991 (NSYSU).

GALLERY

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  By:Liao chunkuei
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  By:Liao chunkuei
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  By:Liao chunkuei
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  By:Liao chunkuei
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  By:Liao chunkuei