Asarum arrhizoma H. Léveillé & Vaniot; A. caudigerum var. leptophyllum (Hayata) S. S. Ying; A. caudigerum var. triangulare (Hayata) S. S. Ying; A. leptophyllum Hayata; A. leptophyllum var. triangulare Hayata.

Herbs. Rhizomes vertical, 2-4 mm in diam., internodes less than 1 cm. Leaves paired; petiole 5-20 cm, villous; leaf blade adaxially dark green with white blotches along veins, broadly ovate, triangular-ovate, or ovate-cordate, 4-10 × 3.5-10 cm, abaxial surface densely pubescent, adaxial surface sparsely pubescent, base auriculate or cordate, lateral lobes 3-4 × 3-3.5 cm, apex acute or long acuminate; cataphylls ovate or ovate-lanceolate, 0.8-1.3 × 0.4-0.6 cm. Peduncle erect to ascending, 1-2 cm. Calyx green to purplish green, ± campanulate, 2-5 × 1-2 cm; sepals free beyond attachment to ovary, abaxially white villous; pseudotube subglobose, 0.6-1.0 × 0.9-1.5 cm; lobes erect or spreading, 1-3 × 0.4-1.2 cm, base ovate-oblong, apex abruptly narrowed to a slender cauda 10-25 mm. Stamens 12; filaments as long as anthers; connectives extended beyond anthers, ligulate to awl-shaped. Ovary inferior. Styles connate, apex 6-cleft, lobes entire; stigmas terminal. Fl. Mar-May.

This species is used medicinally, know as 土细辛 (tu xi xin).

Mixed forests, mountain slopes, along streams; 300-1700 m. Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Sichuan, Taiwan, Yunnan [Vietnam].