1. Lemna trisulca Linnaeus, Sp. Pl. 2: 970. 1753.
品藻 pin zao
Fronds (except when flowering or fruiting) submersed, 3-50 coherent in one group and often forming branched chains, attenuate at base into green connecting stalk 2-20 mm, green and subhyaline, sometimes purplish, narrowly ovate to elliptic, 3-15 mm (without stalk), 2-3.5 × as long as wide, flat, without papillae on upper surface, margin denticulate distally; veins 3, rarely 1, central vein approximating apex, lateral veins ca. 1/2 of frond length. Root 0.5-2.5 cm, often lacking, sheath not winged, apex mostly pointed. Turions absent. Flowering and fruiting fronds free floating on water surface, 1-5 coherent, 3-5 mm. Ovary with 1 ovule; utricular scale with narrow opening at apex. Fruit laterally winged toward apex. Seed with 12-18 distinct ribs. Fl. (rare) May-Sep. 2n = 20, 40, 42, 60, 63, 80.
Lakesides, spring pools, ponds; in regions with cool temperate climate; sea level to 3000 m. Anhui, Hebei, Heilongjiang, Hubei, Jiangsu, Nei Mongol, Shaanxi, Shanxi, Sichuan, Taiwan, Xinjiang, Yunnan, Zhejiang [worldwide except South America].