6. Senna occidentalis (Linnaeus) Link, Handb. 2: 140. 1831.
望江南 wang jiang nan
Cassia occidentalis Linnaeus, Sp. Pl. 1: 377. 1753.
Subshrubs or shrubs, erect, 0.8-1.5 m tall, glabrous, few branched. Branches herbaceous, ribbed; roots blackish. Leaves ca. 20 cm; stipules caducous, triangular to lanceolate, 1-2 cm, membranous; petiole 3-4 cm, with a large, brown, ovoid gland near base; petiolule 1-2 mm, with a rotten smell when kneaded; leaflets 3-5(or 6) pairs, ovate to ovate-oblong, 4-10 × 2-3.5 cm, membranous, base rounded, apex acuminate. Corymbose racemes few flowered, axillary or terminal, ca. 5 cm; bracts caducous, linear-lanceolate. Flowers ca. 2 cm. Sepals unequal, outer ones suborbicular, ca. 6 mm in diam., inner ones ovate, 8-9 mm. Petals yellow, purplish veined, 2 outer slightly larger, shortly clawed. Fertile stamens 7, anthers opening by apical pores, reduced stamens 3, without anthers or with tiny anthers. Ovary tomentose; style glabrous. Legume brown, with pale thick margins, strap-shaped, falcate, flattened, 10-13 × ca. 1 cm, with septa between seeds. Seeds 30-40, flat, orbicular, 3-4 mm in diam. 2n = 24, 26*, 28*, 56*.
Among shrubs on riverbanks, wilderness tracts, hills, sparse forests, wastelands near villages. S regions of China [native to tropical America; widely introduced in the tropics and subtropics elsewhere].