Herbs perennial, glabrous, with horizontal rhizomes. Stems erect. Lower leaves alternate, much smaller or scalelike. Upper leaves in a terminal whorl. Flowers solitary, axillary, pedicellate, (5--)7(--9)-merous, without bracts. Calyx parted nearly to base, persistent. Corolla white, rotate, deeply parted; lobes contorted in bud. Filaments connate basally into a hyaline ring; anthers basifixed, linear, apex obtuse. Ovary globose; style filiform. Capsule globose, dehiscing by 5(--7) valves. Seeds few, reticulate.

Two species distributed in Europe, Asia and NW North America; one species occurs in China.