Flora of North America species comparison

Populations of subsp. heterophylla were determined by W. Dietrich and W. L. Wagner (1988) to be self-incompatible. It occurs in a narrow range from eastern Texas (Austin, Bastrop, Brazos, Cass, Chambers, Cherokee, Dallas, Freestone, Gonzales, Gregg, Hardin, Harris, Henderson, Hopkins, Houston, Jasper, Lee, Leon, Liberty, Limestone, Nacogdoches, Newton, Robertson, Rusk, Sabine, San Augustine, San Jacinto, Smith, Sutton, Travis, Tyler, Upshur, Van Zandt, Victoria, Waller, and Wood counties) and southwestern Louisiana (Caddo, Calcasieu, Erwin, Natchitoches,and Winn parishes). It is known from several historical specimens in St. Louis, Missouri, as an adventive but is apparently no longer growing in that area.

Oenothera variifolia Steudel is a superfluous name that pertains here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera 21, species 582 (16 genera, 246 species in the flora).

Onagroideae encompass the main lineage of the family, after the early branching of Ludwigia (R. A. Levin et al. 2003, 2004). This large and diverse lineage is distinguished by the presence of a floral tube beyond the apex of the ovary; sepals deciduous with the floral tube, petals, and stamens; pollen shed in monads (or tetrads in Chylismia sect. Lignothera and all but one species of Epilobium); ovular vascular system exclusively transseptal (R. H. Eyde 1981); ovule archesporium multicellular (H. Tobe and P. H. Raven 1996); and change in base chromosome number from x = 8 in Ludwigia to x = 10 or x = 11 at the base of Onagroideae (Raven 1979; Levin et al. 2003). Molecular work (Levin et al. 2003, 2004) substantially supports the traditional tribal classification (P. A. Munz 1965; Raven 1979, 1988); tribes are recognized to delimit major branches within the phylogeny of Onagroideae, where the branches comprise strongly supported monophyletic groups of one or more genera.

(Discussion copyrighted by Flora of North America; reprinted with permission.)