Glabrous, scapose, perennial, aquatic or swamp, herbs (in ours), with latex. Leaves erect, rarely floating or submerged, basal; petiole with an expanded sheathing base. Leaf lamina entire, simple. Inflorescence compound or simple, composed of whorls of branches or flowers; bracts 2 or 3 at the base of each whorl and sometimes several bracteoles. Flowers actinomorphic, bisexual or unisexual. Sepals 3, persistent, herbaceous. Petals 3, rarely 0. Stamens 3,6,9 or more. Carpels superior, 3-many, 1-locular. Fruit a cluster of achenes, arranged either spirally or in a single whorl.