Flora of North America species comparison

Species 7 (7 in the flora).

Species of Eremothera are found mainly in the interior deserts and bordering areas of the western United States.

R. A. Levin et al. (2004) found strong molecular support for paraphyly in the broadly delimited Camissonia of P. H. Raven (1969). There was some support for a clade of Camissonia and Eremothera and another clade of Camissoniopsis, Neoholmgrenia, and Tetrapteron (Levin et al.), but without morphological features linking the members of these two clades. The monophyletic subclades of these two clades were recognized as genera by W. L. Wagner et al. (2007) whereas they were all treated by Raven as clearly distinguishable sections. Raven recognized four distinct groups within Eremothera (as Camissonia sect. Eremothera): E. refracta and its autogamous derivative, E. chamaenerioides; the very diverse E. boothii (with six subspecies) and two rare autogamous derivatives, E. gouldii and E. pygmaea; the local clay endemic E. nevadensis; and the widespread autogamous and often cleistogamous E. minor. Levin et al. included one species from each of these four groups in their molecular analyses and found strong support for Eremothera as circumscribed by Raven and maintained by Wagner et al. Eremothera is well defined by white petals that open in the evening and an entire, subglobose stigma; some species are visited by moths at anthesis and by bees the following morning (Raven). Reproductive features include: self-incompatible (E. boothii, E. refracta, and, possibly, E. nevadensis) or self-compatible; flowers vespertine; outcrossing and pollinated in the evening by small moths and the following morning by bees, in E. boothii subsp. decorticans by large oligolectic andrenid bees (E. G. Linsley et al. 1963, 1964, 1973), or autogamous, rarely cleistogamous (Raven).

(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.)