20. Potamogeton nodosus Poiret in Lamarck, Encycl., Suppl. 4: 535. 1816.
小节眼子菜 xiao jie yan zi cai
Potamogeton indicus Roxburgh (1820), not Roth (1818); P. malaianus Miquel.
Plants perennial, in fresh water. Rhizome terete, slender to robust. Stems usually simple or occasionally sparsely branched, terete, 1.5-2 mm in diam. Leaves dimorphic; stipules axillary, convolute, 2-4 cm, membranous, amplexicaul. Submerged leaves petiolate; petiole 0.2-1.5 × length of blade; blade lanceolate or narrowly lanceolate, (7-)11-21-veined, apex obtuse, often decaying early. Floating leaves opaque; blade elliptic or ovate-elliptic, 3-6 × 1.5-3 cm, leathery, (11-)15-23-veined, base cuneate or obtuse, apex acute or slightly obtuse. Spikes cylindric, densely flowered; peduncles 4-6 cm, thicker than stem. Carpels 4. Fruit obovoid, 3-4 mm, abaxial keel distinct. Fl. and fr. Jul-Sep. 2n = 52.
Ponds and channels by lakes, usually in slightly alkaline water. N Shaanxi, Xinjiang, Yunnan [Bangladesh, India, Indonesia, Japan, Kazakhstan, Myanmar, Nepal, New Guinea, Pakistan, Russia, Sri Lanka, Tajikistan, Thailand, Turkmenistan, Uzbekistan, Vietnam; Africa, SW Asia, Europe, North and South America, Pacific islands].