无根萍 wu gen ping

Lemna globosa Roxburgh, Fl. Ind., ed. 1832, 3: 565. 1832.

Fronds free floating on or just below water surface, green on upper surface, transparent green on lower surface, ovoid, 0.4-0.8 mm, 1.3-2 × as long as wide, 1-1.5 × as deep as wide, rounded or slightly pointed at apex; papillae absent. Turions sometimes present, whitish green, globose, 0.2-0.8 mm. Fl. (very rare) Jun-Sep. 2n = 16, 23, 30, 40*, 46, 50, 60.

Lakesides, pools, ponds, ditches; in regions with warm-temperate to tropical climate; sea level to 1300 m. Fujian, Guangdong, Hainan, Henan, Hubei, Jiangsu, Jilin, Sichuan, Taiwan, Yunnan, Zhejiang [Bangladesh, Cambodia, India, Indonesia, Japan, Laos, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Singapore, Sri Lanka, Thailand, Vietnam; introduced in North and South America].

In FRPS (13(2): 211. 1979), the name Wolffia arrhiza (Linnaeus) Horkel ex Wimmer was misapplied to this species.