It usually appears as branched stems with floating leaves in whorls of 3. The leaves have sharply toothed margins and the plant is rough to touch mainly because of the 1 - 12 small sharp teeth or spines that occur on the lower midrib of the leaves. Leaves occur in whorls of 3 to 8. The sheath from which the leaves grow is also toothed on either side. Naiad spreads rapidly because it can spread by both fragmentation and seed production.
Water chestnut is an emersed or floating plant.
The flower of Trapa natans has 4 white petals with 4 green sepals. The fruit of this plant is a nut enclosed in a thorny calyx which has 4 sharp spines. It has large showy purple flowers. The leaves are leathery and somewhat egg shaped with parallel veins. This is one of the most common water garden plants.