Cal-lobes 5, much longer than the coarsely 10- ribbed tube; pet 5, without auricles or appendages; stamens 10; styles (4)5; capsule dehiscent by (4)5 ascending teeth; annual with opposite, entire, exstipulate lvs. 2, Eurasia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.