You might know this plant from Chinese groceries or Chinese restaurants. What is sold there as `water-chestnut` (and many people consider to be the fruit of Trapa natans) is the storage bulb of a spike-rush. Closely related to our native spike-rush it is probably the only member of this genus that is used regularily as a source of food. In China it can almost be ragarded as staple food.

In Central Europe the plant is best kept during summer in very shallow water in a sunny position. If you want to harvest fruit the plant will need a lot of fertilizer and a lot of soil to spread in. In an optimum position it will grow as high as one and a half meter. The chestnuts are harvested in autumn. They develope at the end of the roots and got to be dug up. Peeled before cooking than can be used as a crispy ingredient for Asiatic dishes.

We keep our plants in containers for they are not fully hardy here. Yet they have survived winter temperatures as low as -15° C here. In warmer regions it may be worth a try to grow them outside.