Flora of North America species comparison

Subspecies 2 (1 in the flora).

H. F. Towner (1977) found that Oenothera tubicula is self-incompatible and diurnal with opening times just prior to sunrise. It occurs primarily on limestone soil in arid lowlands, but occasionally in montane areas, from Guadalupe County, New Mexico, south to western Texas, northeast to Howard County, Texas, and south to northern Zacatecas, south-central Nuevo León, and southwestern Tamaulipas, 600–1800 m. Subspecies strigulosa (Towner) W. L. Wagner & Hoch is known only from rocky, open sites and canyons in relatively montane areas, sometimes in pine forests in southernmost Coahuila, south-central Nuevo León, and southeastern Tamaulipas, from 1500 to 2300 m. It differs in being strigillose on the ovary and distally on stems, leaves linear to narrowly lanceolate, and the petals fading red or purple.

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

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.)