Fls sessile or subsessile in the middle and upper axils, 1-several per axil, forming a dense or interrupted false spike, the lower fls cleistogamous, with reduced or abortive cor, the upper fls with normal, regular, wide open cor, the 5 lobes longer than the tube; cal-lobes 5, or only 3 or 4 in cleistogamous fls; stamens free, the short filaments expanded and ciliate at base; ovary mostly trilocular with axile placentas, varying to unilocular and with parietal placentas; stigma (2)3-lobed; capsules linear to ellipsoid or clavate, opening by pores at or usually above the middle; seeds numerous; annuals with toothed lvs. 8, mostly N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.