Wikipedia Article About Water caltrop on Wikipedia The water caltrop or horned water chestnut is a floating annual aquatic plant, growing in slow-moving water up to 5 meters deep, native to warm temperate parts of Eurasia and Africa. It bears ornately shaped fruits, each containing a single very large starchy seed. It has been cultivated in China for at least 3000 years for these seeds, which are boiled and sold as an occasional streetside snack in the south of that country.