Shortly stoloniferous, forming dense mats; usually submerged except for capitulum. Leaves 3- 10 cm, 3-5 mm wide at the base, linear-subulate, pellucid, with a reticulum of opaque veins. Scape 7-20(-150) cm, 1(-3) from each rosette, fragile, the lower part enclosed by a loosely sheathing leaf. Capitulum 3-8 x 6-11 mm, hemispherical. Bracts 2-3 mm, greyish. Perianth of 2 whorls, each of 2 segments; those of female flowers c. 2 mm, free, greyish-black; outer segments of male flowers 3 mm, free, the inner united below, yellowish-grey. Inner segments of all flowers with black apex and conspicuously white-ciliate. Ovary 2-lobed; stigmas 2; seed 1 mm, smooth.
Margins of peaty lakes.
Some authors separate the American plant as E. pellucidum Michx, Fl. Bor. Amer. 2: 166 (1803), mainly on the grounds of its different chromosome number (2n = 32), but the morphological differences are very slight, and until these differences and the chromosome numbers have been shown to be constant throughout the two populations they are best regarded as conspecific.