Oenothera subsect. Stipogaura (P.H. Raven & D.P. Greg.) W.L. Wagner & Hoch Oenothera subsect. Stipogaura (P.H. Raven & D.P. Greg.) W.L. Wagner & Hoch in Syst. Bot. Monogr. 83: 169. 2007 sec. Wagner & al. 2007