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 12 (11 in the flora).

Species of Camissonia occur in desert scrub, grasslands, or pinyon-juniper woodlands, on brushy or open slopes and flats, washes, and, sometimes, on serpentine barrens, at elevations 0 to 2300 meters. Camissonia campestris and C. kernensis are self-incompatible diploids; C. pusilla and C. sierrae are self-compatible diploids; C. contorta is an autogamous hexaploid; the other species are autogamous tetraploids. Identification of the polyploid species of Camissonia is aided by their pollen having a high proportion of grains with more pores, usually 4 or 5, than typical 3-pored pollen in Onagraceae. This can be observed under low magnification (for example, 10\×) since 3-pored pollen is triangular, while 4-pored is quadrangular, and 5-pored is pentangular.

P. H. Raven (1969) delineated a group of four closely related species (Camissonia kernensis, C. parvula, C. pubens, and C. pusilla), marked by having sepals reflexed separately (rather than in pairs), which occur mainly in the Great Basin. Of the remaining species of Camissonia in the flora area, several (C. benitensis, C. campestris, C. integrifolia, C. lacustris, and C. sierrae) have more or less restricted ranges within California, or (C. strigulosa) extend also to Baja California, Mexico, or (C. contorta) to Washington, Idaho, and disjunctly to Vancouver Island, British Columbia. Camissonia dentata (Cavanilles) Reiche is the twelfth species in the genus, disjunct in western South America from southern Peru southward into Chile and Argentina.

W. L. Wagner et al. (2007) departed significantly from the most recent monograph by P. H. Raven (1969) in the delimitation of Camissonia based on the molecular analysis (R. A. Levin et al. 2004); they recognized eight genera in addition to the much reduced Camissonia: Camissoniopsis, Chylismia, Chylismiella, Eremothera, Eulobus, Neoholmgrenia, Taraxia, and Tetrapteron. Raven noted that Camissonia was the most heterogeneous genus in Onagreae, consisting of sharply distinct sections. He further noted that the capitate or subglobose stigma found in Camissonia, by which he distinguished the genus from the broadly circumscribed Oenothera of P. A. Munz (1965), was also found in Gayophytum, Gongylocarpus Schlechtendal & Chamisso, and Xylonagra Donnell Smith & Rose, thus the primary defining character state for the genus at that time is a plesiomorphy (P. C. Hoch et al. 1993). The redefined Camissonia is morphologically delimited by having subterete capsules that are more or less swollen by seeds, linear to narrowly elliptic leaves, and glossy seeds that are triangular in cross-section and mostly smaller than 1 mm in length; and flowering only at the distal, not basal, nodes; and is without ultraviolet reflectance pattern on petals (Raven). Reproductive features include: self-incompatible (C. campestris, C. kernensis) or self-compatible; flowers diurnal; outcrossing and pollinated by bees (E. G. Linsley et al. 1963, 1963b, 1964, 1973), or autogamous, rarely cleistogamous (Raven).

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