Herbs perennial, glabrous. Leaves decussate or alternate on upper part of stem, sessile. Flowers solitary, axillary, nearly sessile or short pedicellate. Calyx petaloid, 5-parted to ± middle. Corolla absent. Stamens 5, attached at base of calyx and alternate with its lobes; anthers cordate-ovate, dorsifixed. Ovary ovoid; style filiform; stigma capitate. Capsule globose, 5-valved.

A single species widely distributed in the N temperate zone.