Young plants initially start with a seedling stem with roots growing in mud at the bottom of the water; further adventitious roots are produced at intervals along the stem, which may hang free in the water or anchor into the bottom. It grows indefinitely at the stem tips, and single specimens may reach lengths of or more. The
leaves are bright green, translucent, oblong, 6–17 mm long and 1–4 mm broad, borne in whorls of three (rarely two or four) round the stem. It lives entirely underwater, the only exception being the small white or pale purple
flowers which float at the surface and are attached to the plant by delicate stalks. These stalks, or
hypanthia, are the lower part of the petals joined to form a
floral tube. This floral tube can be up to in length, while only 1 mm in width, for a length to width ratio of 300 fold. However, according to one article, this ratio can sometimes be as much as one thousandfold. It is
dioecious, with male and female flowers on different plants. The flowers have three small white petals; male flowers have 4.5–5 mm petals and nine
stamens, female flowers have 2–3 mm petals and three fused
carpels. The
fruit is an ovoid
capsule, about 6 mm long containing several
seeds that ripen underwater. The seeds are 4–5 mm long, spindle-shaped and smooth. It flowers from May to October. It grows rapidly in favorable conditions and can choke shallow ponds, canals, and the margins of some slow-flowing rivers. It requires summer water temperatures of 10–25 °C and moderate-to-bright light levels. == Cultivation and uses ==