Aquatic or marsh plants. Roots fibrous, rarely tuberous. Leaves pinnate; leaflets linear to oval or ovate. Peduncles terminal or axillary. Calyx teeth evident or obsolete. Petals white. Involucre of entire or incised bracts. Involucel of linear bractlets. Fruit ovoid to oblong; ridges prominent, thickened, corky; furrows 1-3-vittate. Inner seed face plane.