大青薯 da qing shu

Dioscorea tarokoensis Hayata.

Rootstock unknown. Stem twining to right, slender, glabrous. Leaves usually opposite, simple; petiole 0.5--2 cm; leaf blade abaxially whitish, obovate-oblong or oblong to ovate-lanceolate, wider in juvenile leaves, 2--7(--9) × 0.7--4 cm, papery, glabrous, basal veins 3 or 5(or 7), base rounded, margin entire, apex acute to acuminate, usually appearing rather withered. Male spikes solitary or 2 or 3 together, 2--3 cm, or in short, axillary panicles; rachis obviously zigzagged. Male flowers: sessile; bracts purplish brown dotted, triangular-ovate, apex long acuminate; perianth lobes purplish brown dotted, outer ones orbicular or broadly ovate; stamens 6. Female spikes usually solitary or paired, 3--10 cm. Female flowers: bracts ovate, apex acuminate; outer perianth lobes broadly ovate; staminodes 6. Capsule not reflexed, oblate, ca. 1.5 cm, glabrous; wings 1.2(--1.5) cm wide. Seeds inserted near middle of capsule, winged all round. Fl. May--Jun, fr. Jul--Sep.

* Scrub forests, mountain slopes, valleys, along rivers, roadsides; 300--900 m. W Fujian, Guangdong, Guangxi, Taiwan.