A Taxonomic Study on Dioscorea of Taiwan － Dioscorea doryphora
山羊百科，林文智老師的植物、山岳、攝影紀錄
- Chun Kuei Liao chunkuei.liao@gmail.com 2000/06
8. Dioscorea doryphora Hance in Ann. Soc. Nat. n.s. 5:244. 1866; Matsumura & Hayata, Enum. Pl. Formos. 433. 1906; Kawakami, List Pl. Formos. 122. 1910; Knuth in Engl. Pflansenr. 87(4-43):261. 1924; Sasaki, List Pl. Formos. 114. 1928; Nemoto, Fl. Jap. Suppl. 1084. 1936; Yamamota in Journ. Soc. Trop. Agr. 10:181. 1938; Liu, T. S. & T. C. Huang, Bot. Bull. Acad. Sin. 3(2):145. 1962; Liu, T. S. & T. C. Huang in Fl. Taiwan 5:103. 1978.
－Dioscorea opposita Thunb., Fl. Jap. 151. 1784; Ting, C. T., M. C. Chang & P. P. Ling. in Fl. China 16(1): 103, f.33. 1985 (p.p.).
－Dioscorea swinhoei Rolfe in Journ. Bot. n.s. 6:359. 1882.
HABIT DESCRIBE
A globrous, scandent vine from annual tuber; underground tuber cylindrical; growing down vertically to 1m long; epidermis greyish or yellow-brown; flesh white or ivory; edible, never poisonous; aerial stems terete, ca. 0.5 mm thick, dextrorse, herbaceous, rigid, green or purple; axillary aerial tubers globose or cylindrical, ca. 0.5-2 cm long, 0.5-1 cm in diameter, glabrous, greyish, warty on surface. Leaves alternate, hastate-triangular, ca. 3-9 cm long, 2.5-6 cm wide, deeply 2-5 lobed, acute at apex, entire and slightly undulate at margin, hastate or auriculate at base, chartaceous or subcoriaceous, green, yellow-green, warped inward; nerves 7-9, convave on upper surface and convex on lower surface; petioles ca. 1.5-2 cm long, green or purple, 3-4 ridged, sulcate above, twisted and dilated at both ends; pulvinus bearing thin wings and extending to the lower part of petiole.
Staminate inflorescence axillary, spicate, erect, ca. 2-9 cm long, 1-3 together; spikes with 10-30 flowers; rachis ca. 1 mm thick, 3-4 ridged. Male flower depressed-blobose, ca. 2 mm in diameter, alternate on rachis 2-bracted; outer bract widely ovate, ca. 1 mm long, ca. 1 mm wide, acute at apex, round at base, slightly dentate; inner bract widely ovate, ca. 0.7 mm long, ca. 0.7 mm wide, acute at apex; perianths 6, yellow, cancave insitros, with brown short-lined spots; outer 3 perianths ovate, ca. 1 mm long, 0.7 mm wide, obtuse at apex; inner 3 perianths ovate, ca. 0.9 mm long, 0.7 mm wide, acute at apex; stamens 6, subequal, filaments, terete, ca. 1 mm long, 0.3 mm thick, anthers oblong, ca. 0.9 mm long, 0.5 mm wide, dorsefixed, longitudinally dehiscent; pistillodium rudimentary, conicus, ca. 0.5 mm tall, stigmatiform 3-lobed. Pistillate inflorescence spicate, axillary, solitary, pendulous, up to 5-10 cm long, rigid; spikes with ca. 10 flowers ; rachis ca. 1 mm thick, yellow-green and trigrous with 3-ridged. Female flower trigonus, 3-ridged, ca. 4-5 mm long, ca. 1.5 mm wide, alternate on rachis, 2-bracted; outer bract ovate, ca. 1.9 mm long, 0.1 mm wide,acuminate at apex, thickened at base, green; inner bract ovate, ca. 1.6 mm long, ca. 0.8 mm wide, acuminate and caudate at apex, thickened at base; female perianths 6, yellow, with short-line brown spots, thick; outer 3 perianths circular-ovated, ca. 0.9 mm in diameter, obtuse at apex, round at base; inner perianths similar to outer perianths but smaller, ca. 0.8 mm in diameter; staminodia 6, nippled, bifurcate at apex; outer 3 staminodia , ca. 0.12 mm long, 0.1 mm thick; inner 3 staminodia ca. 0.14 mm long, ca. 0.9 mm thick; ovary inferior, trigonous, green, 3-celled; ovules 2 in each cell, pistillum ca. 0.35 mm tall, stigmas 3, slightly 2-clefed at apex. Fruit capsulate, tripterous, pendulous, transversely elliptic, ca. 1.1 cm long, ca. 1.8 cm wide, retuse at apex, obtuse at base, herberous, green in mature, brown in dry; stipe ca. 2-3 mm long; bracts, perianths and stigmas prisisted; dehiscent reach peducle after dry. Seeds 2 in each cell, orbicular, ca. 3mm in diameter, flattened, dark-brown, membranous wing around, ca. 3 mm wide.
Endemic. The species is common in thicket and roadside thoughtout south of Taiwan, from low to 500m in altitude.
The species is flowering from April to October, and fruiting from May to November.
SPECIMENS EXAMINED
SPECIMENS EXAMINED. Tainan Hsien: Nanhua, C. K. Liao 971 (NSYSU). Kaohsiung Hsien: Kuanyinshan (Tashe Hsiang), S. Z. Yang 2 (PPI). Kaohsiung City: E. Matuda s.n. in 1915 (TFRI), T. Soma 514 (TAI); Shoushan, C. E. Chang 1954 (PPI), C. L. Yeh s.n. in 1985 (PPI 24045, 28223); North-Shoushan, C. S. Yang 111. Pingtung Hsien: Chiuchutang, E. Matuda 516 (TAI); Kenting, C. L. Yeh 858, 861(PPI), Y. L. Chung 692 (PPI), Chang, Yeh & Chune s.n. in 1984 (PPI 23222, 23347, 23362), C. C. Chuang & M. T. Kao 3975 (TAI); Laiyi, T. C. Huang 16080 (TAI); Linan (Chunjih Hsiang), C. L. Yeh 820 (PPI); Paoli (Checheng Hsiang), S. Z. Yang 888, 1024, 24082 (PPI); Santimen, S. Suzuki 11330 (TAI); Sheting, S. Z. Yang s.n. in 1984 (PPI 22267); Tawushan, Wanan, C. L. Yeh 723 (PPI). Taitung Hsien: Chihpen, E. Matuda s.n. in 1918 (TFRI 5209); Hsinfeng, S. Sasaki s.n. in 1933 (TAI).
