A water plant, it requires a rich soil, preferably growing in still water. It can be grown in still or slowly flowing water. In cultivation in temperate greenhouses, the plant is often grown as an annual. It requires about 0.75 cubic metres of root run. This species is not very cold hardy. One report says that it succeeds in zone 8 which would mean that it tolerates temperatures down to between -5 and -10°c but this must be viewed with some doubt. It is unlikely to succeed outdoors in Britain, at least when grown as a perennial. Frequently cultivated as an edible plant in China and India, the seeds are normally available in Chinatown markets in the West.

Fruit. Soft and pulpy, it is about the size of a small orange. It is highly esteemed in China as a cooling tonic food. Seed - fresh or dried. The seed is about the size of a pea, each fruit containing from 8 to 15 seeds. The seed is usually roasted and then eaten. It is also used as a source of starch. A nutritional analysis is available. Very young stalks and rhizomes. Rich in starch.

Seed - best sown as soon as it is ripe, the seed has a short viability and must not be allowed to become dry. Sow the seed in pots in a greenhouse at about 21°c and immerse the pots in water. As soon as they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.

Ponds and lakes in lowland, C. and S. Japan.