Herbs perennial, dioecious. Rhizomes thickened. Stems erect, stout, hollow. Leaves simple, alternate, petiolate; leaf blade ovate or ovate-elliptic, margin entire; ocrea oblique. Inflorescence axillary, paniculate. Flowers unisexual. Perianth persistent, 5-parted; outer 3 tepals accrescent and winged on abaxial surface in female flowers. Stamens 8. Styles 3; stigmas fimbriate. Achenes ovoid, trigonous.