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 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.)