五刺金鱼藻 wu ci jin yu zao

Ceratophyllum oryzetorum V. Komarov, Izv. Bot. Sada Akad. Nauk. S.S.S.R. 30: 200. 1932; C. demersum Linnaeus var. pentacorne Kitagawa; C. demersum var. quadrispinum Makino; C. pentacanthum Hayata.

Stems to 1 m. Leaves deep green, 1--2 × dichotomously divided; whorls 2.5--4 cm in diam.; segments linear, 1--2 cm × 3--5 µm, not inflated. Flowers unknown. Achene brown or dark green, 4--5 × 2--3 mm, smooth or slightly tuberculate, margins wingless and spineless, facial spines 2, 0.5--9.5 mm, not decurrent; basal spines 2, 1.5--12.5 mm, straight or curved; terminal spine (persistent style) 2--12.5 mm. Fl. and fr. Jun--Sep.

Ponds, streams. Anhui, Guangxi, Hebei, Heilongjiang, Hubei, Jilin, Liaoning, Nei Mongol, Ningxia, Shandong, Taiwan, Zhejiang [Japan, Korea, Russia (Far East)].