纤细薯蓣 xian xi shu yu

Rhizome horizontal, irregular. Stem twining to left, glabrous. Leaves alternate, sometimes 3- or 4-whorled at stem base, simple; petiole 7--12 cm; leaf blade drying green or brownish, cordate, 10--18 × 6.5--11 cm, pruinose, glabrous, basal veins 7 or 9, base broadly cordate or subtruncate, margin entire or slightly undulate, apex acuminate. Male spike irregularly branched, laxly few flowered; rachis slender. Male flowers: solitary, rarely in cymules of 2 or 3 at inflorescence base, sessile; bracts ovate, membranous; bracteoles shorter and narrower than bracts; perianth saucer-shaped, lobes oblong-orbicular, 1.5--2 mm; stamens 3, anther connective ca. 1/2 as wide as anther; staminodes 3, inserted at margin of receptacle, clavate. Female spike solitary, laxly few flowered, to 7 cm. Female flowers: staminodes 6. Capsule reflexed, brown, oblong-ovoid, 2--2.2 cm, apex truncate; wings 1--1.1 cm wide. Seeds inserted near middle of capsule, ca. 1 cm in diam. (ca. 0.5 cm excluding wing), winged all round. Fl. May--Aug, fr. Jun--Oct.

Open forests, mountain slopes; 200--2200 m. S Anhui, N Fujian, SW Hubei, E Hunan, Jiangxi, Zhejiang [Japan].

Chinese collections of this species have entire leaves with little or no suggestion of an undulate margin, whereas Japanese collections have leaves with an undulate to obscurely bluntly lobed margin. The type is from Japan.