Flora of North America species comparison

Genera 22, species 664 (17 genera, 277 species in the flora).

Members of the Onagraceae are especially richly represented in North America. The family comprises annual and perennial herbs, with some shrubs and a few small to medium-sized trees. Most species occur in open habitats, ranging from dry to wet, with a few species of Ludwigia aquatic, from the tropics to the deserts of western North America, temperate forests, and arctic tundra; some species of Epilobium, Ludwigia, and Oenothera can be weeds in disturbed habitats. Members of the family are characterized by 4-merous flowers (sometimes 2-, 5-, or 7-merous), an inferior ovary, a floral tube in most species, stamens usually two times as many as sepals, and pollen connected by viscin threads. Flowers are usually bisexual, sometimes unisexual, and plants are gynodioecious, matinal, diurnal, or vespertine, self-compatible or self-incompatible, often outcrossing and then pollinated by a wide variety of insects or birds, or autogamous (P. H. Raven 1979; W. L. Wagner et al. 2007).

Onagraceae are known in considerable systematic detail, and information is available on comparative breeding systems and pollination biology, on chromosome numbers and cytogenetic relations, often involving translocations, and on vegetative, floral, and seed anatomy, palynology, and embryology. The phylogeny of the family is known in reasonably good detail, with most parts of the trees generally well-supported.

The suprageneric and generic classification presented by W. L. Wagner et al. (2007) differs in a number of ways from the previous classification (P. H. Raven 1979, 1988). Onagraceae are divided into two subfamilies based on a fundamental basal split recognized in all phylogenetic studies (R. H. Eyde 1981; P. C. Hoch et al. 1993; R. A. Levin et al. 2003, 2004; V. S. Ford and L. D. Gottlieb 2007), with Ludwigia on one branch (as Ludwigioideae), and the rest of the family on a second branch (as Onagroideae). Onagroideae are subdivided into six tribes: Circaeeae (including Fuchsieae), Epilobieae, Gongylocarpeae, Hauyeae, Lopezieae, and Onagreae. The Epilobieae and Onagreae are diverse; together they constitute fully two-thirds of the species in the family and include 15 of the 22 genera. The classification following Wagner et al. can be viewed on the Onagraceae web site by Wagner and Hoch at http://botany.si.edu/Onagraceae.

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

Species 14 (13 in the flora).

Camissoniopsis proavita (P. H. Raven) W. L. Wagner & Hoch is known from northern Baja California, Mexico. It is a diploid, closely related to C. micrantha but differing in having numerous flowers in the basal rosette, which is densely leafy.

All species of Camissoniopsis occur near coasts or on dry slopes or desert flats inland from 0–2500 m. R. A. Levin et al. (2004) found strong molecular support for Camissoniopsis in a clade with Neoholmgrenia and Tetrapteron. Camissoniopsis was segregated from Camissonia as delimited by P. H. Raven (1969). Camissoniopsis is distinguished by having 4-angled fruits, at least when dry, and not swollen by seeds, dull seeds usually smaller than 1 mm, and by flowering from both basal and distal nodes (Raven). Relationships within Camissoniopsis are complex and reticulate. Several diploids (especially C. hirtella) appear to have contributed to the formation of the tetraploids and, in turn, the hexaploids (Raven), and, as a result, are very similar morphologically to each other. Identification of the polyploid species of Camissoniopsis is aided by their pollen having a high proportion of grains with higher number of pores than typical Onagraceae 3-pored pollen, usually 4- or 5-pored. This can be observed under low magnification (for example, 10\×) since the 3-pored pollen is triangular while the 4-pored is quadrangular and 5-pored is pentangular. Raven proposed Camissonia sect. Holostigma as a new combination based on Spach’s generic name. He was unaware that Holostigma Spach, like Agassizia Spach, is a later homonym and thus illegitimate; however, he satisfied all requirements for valid publication of a new sectional name in Camissonia. Reproductive features include: self-incompatible (C. cheiranthifolia and C. bistorta) or self-compatible; flowers diurnal; outcrossing and pollinated by bees (E. G. Linsley et al. 1963, 1964, 1973) or autogamous (Raven).

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