1a. Hydrilla verticillata var. verticillata
黑藻(原变种) hei zao (yuan bian zhong)
Serpicula verticillata Linnaeus f., Suppl. Pl. 416. 1782; Elodea verticillata (Linnaeus f.) F. Mueller; Hydrilla dentata Caspary; Udora verticillata (Linnaeus f.) Sprengel; Vallisneria verticillata (Linnaeus f.) Roxburgh.
Leaves 0.7-1.7 cm × 1-1.8 mm. Fruit with 2-9 spinelike projections. Seeds 2-6. 2n = 16.
Ponds, running water. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Liaoning, Shaanxi, Shandong, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Indonesia, Japan, Malaysia, Philippines; Australia, Europe].