The Chinese water chestnut (Eleocharis dulcis; synonyms E. equisetina, E. indica, E. plantaginea, E. plantaginoides, E. tuberosa, E. tumida), more often called simply the water chestnut, is a grass-like sedge grown for its edible corms. The water chestnut is actually not a nut at all, but an aquatic vegetable that grows in marshes, underwater in the mud. It has tube-shaped, leafless green stems that grow to about 1.5 metres. The water caltrop, which is also referred to by the same name, is unrelated and often confused with the water chestnut.
The small, rounded corms have a crisp white flesh and can be eaten raw, slightly boiled, grilled, and are often pickled or tinned. They are a popular ingredient in Chinese dishes. In China, they are most often eaten raw, sometimes sweetened. They can also be ground into a flour form used for making water chestnut cake, which is common as part of dim sum cuisine. They are unusual among vegetables for remaining crisp even after being cooked or canned, because their cell walls are cross-linked and strengthened by certain phenolic compounds. This property is shared by other vegetables that remain crisp in this manner, including the tiger nut and lotus root.
The corms are rich in carbohydrates (about 90 percent by dry weight), especially starch (about 60 percent by dry weight), and are also a good source of dietary fiber, riboflavin, vitamin B6, potassium, copper, and manganese.
If eaten uncooked, the surface of the plants can transmit Fasciolopsiasis.
Raw water chestnuts are slightly sweet and very crunchy. Boiled water chestnuts have a firm and slightly crunchy texture, with a flavor that is very mild, slightly nutty in taste, so it is easily overpowered by any seasonings or sauces the water chestnut with which is served or cooked. Water chestnuts are often combined with bamboo shoots, cilantro, ginger, sesame oil, and snow peas. They are often used in pasta or rice dishes.