Asiasarum heterotropoides (F. Schmidt) F. Maekawa.

Herbs. Rhizomes horizontal, 2-3 mm in diam., internodes 0.1-0.5 cm. Leaves paired; petiole 1-15 cm, puberulent; leaf blade uniformly colored, ovate-cordate to subreniform, 4-9 × 5-13 cm, abaxial surface densely pubescent, adaxial surface pubescent along veins, base cordate, lateral lobes 3-4 × 4-5 cm, apex obtuse or acute; cataphylls subrounded, ca. 0.8 × 0.8 cm. Peduncle recurved at anthesis, erect in fruit, 3-5 cm. Calyx purplish brown, broadly urceolate, 1-1.5 × ca. 1 cm; sepals connate beyond attachment to ovary, abaxially glabrous; tube subcylindric, ca. 1 × 1 cm, adaxially longitudinally ribbed; lobes reflexed, triangular-ovate, ca. 0.7 × 0.9 cm. Stamens 12; filaments slightly longer than anthers; connectives not extended beyond anthers. Ovary superior. Styles free, short, apex shallowly 2-cleft; stigmas lateral. Fl. May.

Material from China belongs to the endemic form, Asarum heterotropoides f. mandshuricum (Maximowicz) Kitagawa (A. sieboldii Miquel var. mandshuricum Maximowicz; Asiasarum heterotropoides (F. Schmidt) F. Maekwa var. mandshuricum (Maximowicz) F. Maekawa); whereas f. heterotropoides is restricted to Japan. The authentic traditional Chinese medicine 细辛 (xi xin).

Forests, mountain slopes, valleys, moist shady areas, occasionally cultivated. in S China. Heilongjiang, Jilin, Liaoning [Japan].