Eleocharis dulcis, the Chinese water chestnut or water chestnut, is a grass-like sedge native to Asia (China, Japan, India, Philippines, etc.), Australia, tropical Africa, and various islands of the Pacific and Indian Oceans. It is grown in many countries for its edible corms.
The water chestnut is not a nut at all, but an aquatic vegetable that grows in marshes, under water, in the mud. It has stem-like, tubular green leaves that grow to about 1.5 m.
The small, rounded corms have a crisp, white flesh and may be eaten raw, slightly boiled, or grilled, and often are pickled or tinned. They are a popular ingredient in Chinese dishes. They are unusual among vegetables for remaining crisp even after being cooked or canned.
It is easy enough to grow water chestnuts at home. The corns or 'bulbs' can be ordered online.
Soak the corns in water until the plants sprout, then plant them in mud and always keep water standing on top.
Pic1-3: growing water chestnuts at home
Water chestnut is part of many frozen Oriental vegetable mixes.
It is also available canned and I have bought it in that form to add to salads.
internet picturesPic4: water chestnuts
Pic7-9: water chestnut dishes