Caulinia minor (Allioni) Cosson & Germain; Fluvialis minor (Allioni) Persoon; Ittnera minor (Allioni) C. C. Gmelin; Najas moshanensis N. Z. Wang.

Stems 4-25 cm tall, 0.5-1 mm in diam. Leaves recurved, 1-3 cm × 0.5-1 mm; sheath ca. 2 mm; auricles truncate to rounded, with more than 10 teeth on upper and outer sides of leaf margin, each side serrulate with 6-12 teeth, apex acuminate. Plants monoecious; flowers yellowish green. Male flowers elliptic, 0.5-1.5 mm; spathe with a short neck, with brownish spine cells at apex; anther 1-thecous. Female flowers ca. 2 mm; style 1-1.7 mm; stigmas 2-lobed. Fruit linear-ellipsoid, 2-3 × ca. 0.5 mm, narrowed and slightly curved at apex. Seeds narrowly ellipsoid, with many rows of transversely elongated ladderlike pits; areoles fusiform. Fl. and fr. Jun-Oct. 2n = 12*, 24*, 36, 46, 56.

Ponds, lakes, paddy fields and channels; below 2700 m. Anhui, Fujian, Guangdong, Guangxi, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Shandong, Taiwan, Xinjiang, Yunnan, Zhejiang [Afghanistan, India, Indonesia (Java), Japan (including Ryukyu Islands), Kazakhstan, Korea, Nepal, Pakistan, Philippines, Sri Lanka, Tajikistan, Thailand, Uzbekistan, Vietnam; Africa, SW Asia, Europe; introduced in North America].