毛芋头薯蓣 mao yu tou shu yu

Dioscorea bonatiana Prain & Burkill; D. dissecta R. Knuth; D. fargesii Franchet; D. firma R. Knuth; D. kamoonensis var. fargesii Prain & Burkill; D. kamoonensis var. straminea Prain & Burkill; D. mairei R. Knuth (1924), not H. Léveillé (1913); D. mengtzeana R. Knuth; D. subfusca R. Knuth.

Tubers usually subovoid; roots fibrous. Stem twining to left, brown puberulent when young, glabrescent. Bulblets present. Leaves alternate, palmately 3- or 5-foliolate; petiole 2--10 cm, very rarely softly prickly at base; leaflets paler abaxially than adaxially, obovate- or lanceolate-elliptic to elliptic, 2--14 × 1--5 cm, densely to sparsely puberulent, sometimes adaxially glabrescent, pinnately veined, base attenuate into indistinct petiolule, margin entire, apex long acuminate; lateral leaflets slightly smaller than middle one, oblique. Male spikes or racemes solitary or 2 or 3(--8) together, rarely branched, dense, to 7 cm, rarely forming axillary panicles to 8 cm; axis pale yellow to reddish spreading pubescent; peduncle densely brown or light yellow puberulent. Male flowers: solitary; pedicel 0.5--1.5 mm; bract and bracteole similar, triangular-ovate, 2--3.5 mm, exceeding perianth and forming an involucel around it, densely brown or light yellow puberulent, apex long acuminate; perianth lobes 1.5--2.5 mm, densely brown or light yellow appressed puberulent abaxially; stamens 3. Female spikes solitary or paired, rarely 3 together, to 24 cm. Capsule oblong to oblong-oblanceolate, 1.5--2(--2.4) cm, puberulent; wings 0.5--0.6(--0.75) cm wide. Seeds inserted near apex of capsule; wing pointing toward capsule base. Fl. Jul--Sep, fr. Sep--Nov.

Secondary scrub forests, forest margins, valleys; 500--2900 m. Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Sichuan, Xizang, Yunnan, S Zhejiang [Bhutan, Sikkim, Vietnam].

Precociously flowering material has been recognized as a distinct species, Dioscorea ochroleuca K. Y. Guan & D. F. Chamberlain (Edinburgh J. Bot. 49: 85. 1992), but the present authors prefer to follow Prain and Burkill, who treated such material as an unusual growth form of D. kamoonensis. Material with deep red hairs was also recognized recently as a distinct species, D. brevifolia K. Y. Guan & D. F. Chamberlain (loc. cit.: 46), but, again, we prefer to include it within the very variable D. kamoonensis in which the indumentum color varies greatly. It should be noted that both names D. ochroleuca and D. brevifolia are invalid as they were based on the invalid names D. kamoonensis var. praecox Prain & Burkill and D. kamoonensis var. brevifolia Prain & Burkill, respectively, and thus lack validating diagnoses.