20. Phyllanthus amarus Schumacher & Thonning, Kongl. Danske Vidensk. Selsk. Skr. 4: 195. 1829.
苦味叶下珠 ku wei ye xia zhu
Annual or biennial, rarely perennial, herbs, 10-170 cm tall or long, erect or prostrate, glabrous throughout; stem simple, base woody, or slightly so and yellowish, straw yellow, or brownish, branched, terete, green at upper part, leaves reduced to lanceolate or triangular scales. Leaves distichous; stipules linear or linear-lanceolate, green; petioles ca. 0.5 mm; leaf blade oblong or elliptic-oblong, 3-8 × 2-4.5 mm, membranous or thinly papery, base rounded, apex obtuse or rounded and often apiculate; lateral veins 4-7 pairs, slightly conspicuous abaxially, obscure adaxially. Plants monoecious. Flower fascicles along lower part of leafy shoots usually male, those in middle usually often bisexual with 1 female and 1 male flower, those toward branchlet apex often female. Male flowers: pedicel 0.5-1 mm; sepals 5, elliptic or ovate, ca. 0.5 × 0.2 mm, yellowish green, margin membranous, apex abruptly acute; disk glands 5, orbicular or obovate, or spatulate, apex truncate or retuse, ca. 0.1 mm in diam., entire; stamens (2 or)3; filaments completely connate into a column, 0.2-0.3 mm high; anthers sessile, 1 often reduced to a single anther sac (or sometimes only 2 functional anthers present), anther sacs divergent, slits completely confluent, dehiscence oblique to less commonly horizontal. Female flowers: pedicels 0.6-1 mm; sepals 5, obovate-oblong or ovate, 0.8-1 × 0.4-6 mm, margin membranous, apex obtuse or acute; disk flat or subulate, deeply 5-lobed; ovary globose-triangular, ca. 0.5 × 0.5 mm, smooth; styles free, erect or ascending, apex shallowly bifid. Fruiting pedicels 1-1.5 mm, dilated at apex; capsules smooth. Seed sharply 3-angled, 0.9-1 × 0.7-0.8 mm, light brown or yellowish brown, radially and with 5 or 6 straight parallel longitudinal ribs on back, minutely transversely striate with hygroscopic cells which project as hyaline setae with a pronounced notching of lumen. Fl. and fr. throughout year.
Dry fields, roadsides, wastelands, forest margin, scrubby woods; below 100-600 m. Guangdong, Guangxi, Hainan, Taiwan, Yunnan [pantropical weed possibly originating in the Americas].