Aquatic or marsh plants. Roots fibrous or tuberous. Leaves compound, 1-3-pinnate; segments linear to oval or ovate; leaf bases sheathing. Involucre of a few bracts or lacking. Involucel of linear bractlets. Petals white. Calyx teeth prominent, persistent. Styles slender. Fruit oblong to ovoid; ridges subequal, obtuse, corky; furrows univittate; commissure 2-vittate. Inner seed face plane.