Fls in compact, terminal and axillary cymose clusters, perfect, perigynous, the cupulate hypanthium resembling a cal-tube; sep 5; pet none; stamens 1-10; ovary ovoid; styles 2, distinct; ovule one on a basal placenta; hypanthium becoming indurate in fr, crowned by the persistent sep and enclosing the membranous utricle; seed obovoid, beaked at the micropylar end; low herbs with diffusely forking stems and opposite, exstipulate lvs connate at base. 10, Old World.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.