Fls 4-merous, solitary in the axils or forming a terminal raceme or spike, commonly vespertine and ephemeral, but matutinal or diurnal and lasting several days in spp. 13-17; hypanthium usually slenderly tubular and prolonged well beyond the ovary (at least 3 mm in all but one of our spp.), deciduous from the fr; sep at first connate, often with terminal or subterminal appendages, splitting at anthesis and reflexed; pet in most of our spp. yellow, in two white or pink, often large and showy; stamens 8, equal or alternately unequal; anthers versatile (sometimes obscurely so in small fls); sporogenous tissue continuous in each microsporangium; ovary 4-locular; ovules numerous; style ±elongate; stigma with 4 slender lobes stigmatic all around; capsule prismatic to terete or winged, linear to ovoid or obovoid, in some spp. deeply sulcate and strongly angled; herbs with alternate, mostly narrow lvs. (Kneiffia, Hartmannia, Lavauxia, Megapterium, Meriolix, Peniophyllum, Raimannia) 80, New World.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.