Potamogeton lucens L.

Vertical shoots short-lived or biennial, seasonal; stem robust, terete, to 3 m long, much branched from the base; horizontal shoots much branched, robust to very robust, forming dormant apical and lateral multiple winter buds. Floating leaves absent; submerged leaves lanceolate to oblong, petiolate, sometimes the lower ones reduced to phyllodes, lamina 50-150 by 15-30 mm, 9-13-veined, margin serrulate toward the tip, base cuneate, apex mucronate; petioles 3-12(-20) mm; stipules axillary, convolute, 25-50 mm, obtuse or rounded at apex. Spikes cylindrical, contiguous, 30-50 mm; peduncles 50-200 mm, twice as thick as stem. Flowers numerous, with 4 carpels. Fruits 3.2-4 mm long, dorsal keel indistinct. Stem anatomy: Stele of oblong type (rarely trio or proto type). Endodermis of U-type. Interlacunar bundles present, multicellular, in 3 circles, subepidermal bundles present. Pseudo-hypodermis present, 1-layered. Chromosome number: 2n = 52.