Much like Oenothera (and often included therein), but the stigma peltate, entire or often very shallowly and broadly 4-lobed, the receptive surface above-within; sporogenous tissue divided into packets in each microsporangium. (Meriolix, Salpingia) 6, w. N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.