Perennial herb to 1 m tall, the rootstock with both stolons and tubers. Leaves to about 20 cm or so long and wide, arrow-head shaped with long lobes at the base. Submerged leaves linear. Flowers with petals 1-1.5 cm wide, white and with a purple spot at the base; summer. Stamens 20-25.

Often confused with S. montevidensis (which does not have stolons) but the outer parts of the female flower are reflexed and the flower stalk is not distinctly thickened. S. variabilis is sometimes listed but it is possible that plants available under this name are S. sagittifolia.

Eurasia.

Source: Spencer, R. (2005). Alismataceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.