Dioscorea alata

山羊百科，林文智老師的植物、山岳、攝影紀錄

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Dioscorea alata L.

BY:Liao chunkuei　chunkuei.liao@gmail.com

Dioscorea alata L. Sp. Pl. 1033. 1753; Hayata, Ic. Pl. Form. 10: 42, f. 22. 1921; Knuth in Engl. Pflanzenr. 87(4-43):265. 1924; Yamamoto, Suppl. Icon. 3:5. 1927; Sasaki, List Pl. Form. 113. 1928; Prain & Burkill in Ann. Bot. Gard. Callcutta 14(2):302. 1939, pl.123. 1938; Liu, T. S. & T. C. Huang, Bot. Bull. Acad. Sin. 3(2):133. 1962 & Bot. Acad. Sin., Icon. Corm. Sin. 5:568, f.7965. 1976; Liu, T. S. & T. C. Huang in Fl. Taiwan 5:100. 1978; Ting, C. T., M. C. Chang & P. P. Ling. in Fl. China 16(1):117, f.37. 1985.

SYNONYMS

Dioscorea alata var. globosa (Roxb.) Prain

Dioscorea alata var. purpurea (Roxb.) A. Pouchet

Dioscorea alata var. tarri Prain & Burkill

Dioscorea alata var. vera Prain & Burkill

Dioscorea atropurpurea Roxb.

Dioscorea colocasiifolia Pax

Dioscorea eburina Lour.

Dioscorea eburnea Lour.

Dioscorea globosa Roxb.

Dioscorea javanica Queva

Dioscorea purpurea Roxb.

Dioscorea rubella Roxb.

Dioscorea sapinii De Wild.

Dioscorea sativa Munro

Dioscorea vulgaris Miq.

Elephantodon eburnea (Lour.) Salisb.

Polynome alata (L.) Salisb.

HABIT DESCRIBE

A glabrous, scandent vine from annual tuber, up to 15 m long; underground tubers polymorphous, mainly cylindrical, cylindroid or globose, occasionally branched or compressed, up to 1 m long; outer epidermis brown to black, some cultivar’s subepidermis purple; flesh white, ivory or purple, edible, never poisonous; aerial stems dextrorse, herbaceous, branched, green or purple, or brown near the base, occasionally prickly or warty toward the base, quadrangular in cross-section, 2-3 mm thick, with 4-longitudinal ridges which enlarged with undulate-wrinkled, membranous green or purple wings; wing 1-2 mm broad, sometimes inconspicuous; aerial tubers axillary, cylindrical or globose, 3-5 cm long, 1.5-2 cm in diameter, yellow-green, dark-brown or purple, somtimes rooting when on stem. Leaves opposite, or alternate in the juvenile or near the base of stem, chartaceous, glabrous, oblong-triangular, oblong-ovate or oblong -cordate, 8-17(-31) cm long, 6-12(-15) cm wide, acuminate or short-caudate at apex, entire at margin, cordate or auriculate or subhastate at base, smooth on both surfaces; nerves 7-9, prominent on both surfaces; veinlets fine and prominent, bright green at upper surface, yellow-green at lower surface; petioles twisted and dilated at base, sulcate above, 2- or 4-winged, wrinkled and extending to stem, 4-10(-15) cm long, 1-5 mm thick.

Staminate inflorescence axillary, spicate, 1-2 together, or compound to narrowly paniculiform, up to 30 cm long; spikes with upward of 20 flowers, 1.5-2 cm long, with a pair opposite ensiform bracts; rachis greenish, rigid, with 2 longitudinal ridges which narrowly winged at base. Male flowers alternate on the short and zigzag rachis, globose, ca. 1.5 mm in diameter, glabrous, 2-bracted; outer bract orbicular, ca. 1.2 mm long, ca. 1 mm wide, acuminate at apex; inner bract obovate, ca. 1 mm long, ca. 0.9 mm wide, acute at apex, round at base, yellow-green; perianths 6, yellow; outer 3 perianths elliptic-ovate, ca.1.8 mm long, ca.1.1 mm wide, obtuse and thickened at apex; inner 3 perianths spatulate or obovate, ca. 1.3 mm long, ca. 0.8 mm wide; stamens 6, subequal, shorter than perianths, filaments terete , ca.0.4 mm long, anthers oblong, ca.1.7 mm long, ca.0.8 mm wide, dorsifixed, longitudinally dehiscent; pistillodium rudimentary, conicus, ca.0.2 mm tall, stigmatiform 3-lobed. Pistillate inflorescence racemose, axillary, solitary or paired, decurved, rigid, up to 60 cm long, with ca. 20 flowers remotely arranged; rachis angled or narrowly winged at base. Female flowers glabrous, green, ca. 8 mm long, ca. 3-5 mm wide, with 2 basal bracts; pedicel ca. 1-2 mm long; perianth segments 6; outer 3 perianth segments ovate, short-acuminate at base; inner perianth segments obovate, thick; staminodia 6; ovary inferior, 3-celled; ovules 2 in each cell; stigmas 3, 2-cleft at apex. Fruit capsulate, pendulous, brownish, obovate, ca. 2.5 cm long, ca. 1.5 cm wide, tripterous, slightly retuse at apex, obtuse at base, rigid; stipe 2-3 mm long. Seeds 2 in each cell, orbicular, with broadly membranous wing around.

This species is distributed in south-east Asia,and spread to India, Malaysia, Indoesia, Philippines, and the eastern portion of south-east Asia, included Taiwain, and has been cultivated for a long time in Taiwan. It is flowering from September to October, and fruting in November. Most cultivars do not normally flower.

SPECIMENS EXAMINED

SPECIMENS EXAMINED. Taipei City: Pei-t’ou, Y. Shimada, s.n. in 1914 (TAI); Yangminshan (Sozan), Y. Yamamoto s.n. in 1938(TAI 30756); cult. in TFRI, T. C. Huang s.n. in 1960(TAI 30748, 30750, 30747). Taipei Hsien: Shinments’un, C. K. Liao 985; P’inglin, C. K. Liao 995. Tainan Hsien: Liuchia’ts’un, C. K. Liao 986. Kaohsiung Hsien: Ch’ishan, T. Kawakami & U. Mori s.n. in 1907(TAI 49, 6203, 6204, 30758); Liukei, C. E. Chang 19232 (PPI); Meinung, C. K. Liao 992. Pingtung Hsien: Saichia, C. K. Liao 875, 980, 994; Ts’aoputs’un, C. K. Liao 988; T’aiwu, C. K. LIao 1126. Lanyu: S. Sasaki s.n. in 1926 (TAI 30806, 30751); Y. L. Chung 556 (PPI); C. K. Liao 765,993. Ilan Hsien: Ta-t’ung, S. Suzuki 4916 (TAI); Chinyuehts’un(Ryohen & Mohen), S. Suzuki 6035(TAI).