Flora of North America species comparison

Species 2 (2 in the flora).

Section Kleinia consists of two species of usually open sandy or rocky sites from the Chihuahuan, Sonoran, and southern portions of the Great Basin deserts to the Great Plains, from southern Utah to southeastern Montana and western North Dakota, south to northern Mexico (Chihuahua and Sonora) at 1000 to 3000 m; Oenothera coronopifolia generally occurs at higher elevations than O. albicaulis. As summarized by W. L. Wagner et al. (2007; see also K. E. Theiss et al. 2010), O. albicaulis is diploid (2n = 14) and O. coronopifolia has both diploid and tetraploid (2n = 14, 28) populations. Both species are self-incompatible and the vespertine flowers are pollinated by hawkmoths, especially Hyles and Manduca. P. H. Raven (1979) reported that O. coronopifolia had both self-incompatible and self-compatible populations. Theiss et al. found only self-incompatible plants in one population examined.

Section Kleinia is included within a strongly supported clade with members of sect. Anogra in recent molecular studies (R. A. Levin et al. 2004; M. E. K. Evans et al. 2005, 2009); placement of the subclade of the two sect. Kleinia species within the overall clade is not strongly resolved. For the present, the classification, based on morphology, is maintained until further resolution can be obtained. Section Kleinia can be distinguished by a number of morphological characteristics, including capsule shape, seeds in two rows per locule, and seeds with anatomy similar to that found in sect. Oenothera subsect. Raimannia but unlike that in sect. Anogra (W. L. Wagner et al. 2007; H. Tobe et al. 1987). P. A. Munz (1965) described sect. Kleinia as part of his subg. Raimannia, thus including these two white-flowered species in an otherwise yellow-flowered group because of similarities of the capsules and seeds. This group has been viewed as intermediate between sect. Oenothera subsect. Raimannia and sect. Anogra (Wagner et al.). Although both sects. Anogra and Kleinia have morphological synapomorphies that define them, a section combining them would be united by nodding buds and white petals; both characters are not unique morphological synapomorphies.

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

Genera 13, species 265 (12 genera, 199 species in the flora).

Onagreae account for more than half the total genera in Onagraceae and diversified from a center in southwestern North America (L. Katinas et al. 2004). Delimitation of the tribe by W. L. Wagner et al. (2007) differs from previous ones by the exclusion of Gongylocarpus, now in its own tribe, by the segregation of eight genera (Camissoniopsis, Chylismia, Chylismiella, Eremothera, Eulobus, Neoholmgrenia, Taraxia, and Tetrapteron) from Camissonia, and by the inclusion of three previously separate genera (Calylophus, Gaura, and Stenosiphon) in Oenothera. Within the branch of the family that lacks stipules (Gongylocarpeae, Epilobieae, and Onagreae), the last two tribes form a clade that has very strong molecular support (R. A. Levin et al. 2003, 2004), but no obvious morphological synapomorphy. The clade may be defined by a cytogenetic change from the base chromosome number of x = 11 found in Circaeeae, Gongylocarpeae, and Lopezieae, to x = 18 in Epilobieae, and x = 7 in Onagreae; however, these changes could also have occurred independently. Other than the new chromosome number x = 7, the only apparent morphological synapomorphy for Onagreae alone is pollen with prominent apertural protrusions (J. Praglowski et al. 1987, 1989), a character state also found in Circaeeae (Praglowski et al. 1994). The monophyly of Onagreae has moderate (Levin et al. 2004) to strong support (V. S. Ford and L. D. Gottlieb 2007).

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