1b. Hydrilla verticillata var. roxburghii Caspary, Jahrb. Wiss. Bot. 1: 494. 1858.
罗氏轮叶黑藻 luo shi lun ye hei zao
Leaves 0.7-1.3 cm × 3-4 mm. Fruit smooth, without spinelike projections. Seeds 1-3, usually without embryo. 2n = 24.
Ponds, running water. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [Japan, Malaysia, Philippines; Australia, Europe].
