19. Potamogeton distinctus A. Bennett, J. Bot. 42: 72. 1904.
眼子菜 yan zi cai
Potamogeton fontigenus Y. H. Guo, S. C. Sun & H. Q. Wang; P. franchetii A. Bennett; P. longipetiolatus E. G. Camus; P. perversus A. Bennett.
Plants perennial, in fresh water. Rhizome terete, slender, with apical dormant buds. Stems terete, slender, 1.5-2 mm in diam., simple or rarely sparsely branched. Leaves dimorphic; stipules axillary, convolute, 2-7 cm, membranous, translucent, amplexicaul, often persistent, 11-19-veined; petiole 5-20 cm. Submerged leaves petiolate; blade narrowly lanceolate to lanceolate, herbaceous, often decaying early, 9-17-veined. Floating leaves petiolate; petiole 0.5-2.3 × length of blade; blade opaque, lanceolate to ovate-lanceolate or broadly elliptic, 2-10 × 1-4 cm, leathery, 11-19-veined, base obtuse or sometimes cuneate, apex acute or obtuse. Spikes cylindric, 2.5-8 cm, densely flowered, contiguous; peduncles thicker than stem, 3-10 cm. Carpels (1 or)2(or 3). Fruit broadly obovoid, 2.9-3.7 mm, abaxial keels 3, with a sharp midrib and ± obtuse lateral keels. Fl. and fr. May-Oct. 2n = 52.
Ponds, paddy fields, channels. Fujian, Gansu, Guangdong, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [Bhutan, Indonesia, Japan (including Ryukyu Islands), Korea, Malaysia, Nepal, Philippines, Russia, Thailand, Vietnam; Pacific islands].
The Chinese record of Potamogeton polygonifolius Pourret in FRPS (8: 67. 1992) was based on a misidentification of P. distinctus.