东方茨藻 dong fang ci zao

Najas orientalis Triest & Uotila.

Stems 10-15 cm tall, 0.5-1 mm in diam. Leaves linear to narrowly lanceolate, 1-3 cm × 0.2-1 mm; sheath ca. 2 mm; auricles rounded, minutely serrulate with several teeth on each side; leaf margin minutely serrulate with 6-20 teeth on each side. Plants monoecious; flowers solitary or sometimes 2 together, male flowers in upper axils and female ones throughout. Male flowers elliptic, ca. 1 mm; spathe with a neck, with several brownish spine cells at apex; anther 4-thecous. Female flowers 2-2.5 mm; style ca. 1 mm; stigmas 2-4(or 5)-lobed. Fruit narrowly ellipsoid, 2-2.5 × ca. 0.5 mm. Seeds slightly reniform, with ca. 20 rows of pits; areoles regularly arranged, subsquare; cell walls apparently raised. Fl. and fr. May-Aug. 2n = 12*.

Ponds, channels, paddy fields, slow-moving rivers; below 1800 m. Fujian, Guangdong, Guangxi, Hainan, Hubei, Jiangxi, Jilin, Liaoning, Taiwan, Yunnan, Zhejiang [Japan; Europe].

Najas chinensis is similar to N. foveolata but can be easily separated by its rounded sheath and apparently raised cell walls of the seed coat.