Water chestnuts are crunchy, mildly sweet aquatic vegetables that grow in shallow water, not actual nuts.

What water chestnuts actually are

  • The commonly eaten “Chinese water chestnut” is the underground corm (a swollen stem, like a small tuber) of a grass‑like sedge called Eleocharis dulcis.
  • They grow in marshes, ponds, rice paddies, and other muddy, shallow waters across Asia, tropical Africa, and Oceania.
  • Despite the name, they are not related to tree chestnuts; the name comes from their round shape and brown skin that resembles a chestnut.

There’s also another plant called water chestnut (Trapa species) that produces hard, nutlike fruits (sometimes called water caltrops), but this is different from the crunchy slices you see in stir‑fries.

How they look and taste

  • Fresh water chestnuts have a thin brown skin and white, crisp flesh inside.
  • The texture stays crunchy even after cooking, which is why they’re popular in stir‑fries and dumplings.
  • Flavor is mild, lightly sweet, and a bit nutty, so they soak up sauces and seasonings around them.

How they’re used in food

  • Common in Chinese and other Asian cuisines in stir‑fries, spring rolls, dumplings, curries, and soups.
  • Often sold canned (pre‑peeled and sliced), but fresh ones are sweeter and crunchier when you can find them.

Example: In a vegetable stir‑fry, carrot and bell pepper provide color and sweetness, while water chestnuts add that satisfying crisp bite with each mouthful.

Nutrition and health notes

  • They are low in calories but provide fiber, some B vitamins, and minerals like potassium and manganese.
  • Their high water content and fiber help with fullness and digestion.
  • Naturally gluten‑free and suitable for many diets; people with tree nut allergies usually tolerate them because they are not true nuts (though anyone with allergies should still check with a doctor).

A quick word on the other “water chestnut” plant

  • The Trapa natans water chestnut is an aquatic plant whose floating rosettes can take over lakes and rivers and are considered invasive in parts of North America.
  • It produces hard, spiky fruits sometimes eaten in parts of Europe and Asia, but this is not the same as the crunchy slices in supermarket cans.

TL;DR: When people ask “what are water chestnuts?”, they usually mean the crisp, white corms of the Chinese water chestnut plant, an aquatic vegetable used for its crunch and mild flavor in many Asian dishes—not a real nut at all.

Information gathered from public forums or data available on the internet and portrayed here.