Rhizomatous. Stems usually much less than 1 m. Leaves floating and submerged. Floating leaves lacking flexible joint at top of petiole; lamina ± equal to petiole, ± elliptic, 4-12 cm, ± obtuse at apex, shortly attenuate to cuneate at base, green to brownish, coriaceous. Submerged leaves with longer petiole; lamina to 25 cm, ± lanceolate, obtusish to acute at apex, reticulate-veined, margin minutely denticulate, often withering early. Stipules to 8 cm, conspicuous. Peduncles 4-15 cm. Spikes 3-6 cm. Fruitlets c. 3 mm, obovoid. Fl. 4-8. Lakes, rivers, canals, pools, s.l.-1970 m.
W., C. & E. Europe, Mediterranean area, S.W., C. & S.B. Asia, Africa, N. America.