(modifié de Coste, Flore de la France 1937) :
Plante vivace souvent très allongée, glabre ou pubescente, à souche longuement rampante et rameuse; tiges submergées ou terrestres, radicantes à la base;
Écologie : (répartition d'après la flore) Rivières, étangs, mares, dans toute la France, et en Corse.
Répartition hors de France : Europe ; Asie; Afrique boréale et australe; Amérique du Nord.
(modified from Butcher, British Flora 1961):
NOTE: the French text is more complete and up-to-date
A perennial with two distinct vegetative forms: when it grows in water it is glabrous and has floating Ieaves and a submerged stem 15-60 cm long; when it grows in the wet ground beside the water it has spreading Ieaves and an erect, somewhat tomentose stem 23-38 cm high.
Ecology UK: It is common in pools, slow rivers and wet places throughout the British Isles.
Fleurs : roses, en épi terminal oblong-cylindrique, compact, dressé ; 5 étamines saillantes ; 2 styles soudés la base;
Floraison France : Juin-septembre.
Flowers: 2.5-3.0 mm diam., in rather lax and irregular, terminal, solitary spikes 10 mm diam.; perianth lobes deep pink or whitish, narrowly lanceolate, without glands; stamens 5, becoming longer than the lobes; styles 2.
Flowering UK: Mid July-early Sept
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