Flora of North America species comparison

Species 5 (2 in the flora).

Section Leucocoryne consists of five species that occur from southern Texas, through northern Mexico to the Trans-Volcanic Belt of central Mexico, southward to Guatemala, Nicaragua, and Costa Rica, in openings in pine-oak or conifer forests on slopes or along streams (or arroyos), sometimes along roadsides or other weedy habitats, at 1400–2800(–3250) m elevation.

Species of section Leucocoryne share white petals, have similar capsule shape with a rounded to bluntly acuminate apex, and buds with free tips. All but Oenothera dissecta A. Gray ex S. Watson were formerly included in a more broadly defined sect. Hartmannia. Oenothera dissecta, previously included in sect. Gauropsis (P. A. Munz 1965; W. L. Wagner 1984), was transferred to sect. Leucocoryne, because it has capsules most similar to those of other white-flowered species grouped here (Wagner et al. 2007). All sect. Leucocoryne species are self-compatible (unknown in O. luciae-julianiae W. L. Wagner), the flowers vespertine, pollinated by hawkmoths or autogamous (O. kunthiana and presumably O. luciae-julianiae). Oenothera kunthiana is a PTH species and forms a ring of 14 chromosomes in meiosis; O. luciae-julianiae also appears to be a PTH species, indicated by lowered pollen fertility (Wagner 2004). Section Leucocoryne species are diploid (n = 7), except O. dissecta, which is known exclusively as a tetraploid (n = 14); the chromosomes of O. luciae-julianiae have not been examined.

Oenothera dissecta and O. luciae-julianiae both occur in Mexico. Oenothera dissecta occurs in flats in Durango, Jalisco, San Luis Potosí, and Zacatecas; O. luciae-julianiae occurs in pine-oak forest habitats in the Sierra Madre Occidental from Chihuahua south through Durango, Guanajuato, Nayarit, Jalisco, Michoacán, and Querétaro.

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

Genera 13, species 265 (12 genera, 199 species in the flora).

Onagreae account for more than half the total genera in Onagraceae and diversified from a center in southwestern North America (L. Katinas et al. 2004). Delimitation of the tribe by W. L. Wagner et al. (2007) differs from previous ones by the exclusion of Gongylocarpus, now in its own tribe, by the segregation of eight genera (Camissoniopsis, Chylismia, Chylismiella, Eremothera, Eulobus, Neoholmgrenia, Taraxia, and Tetrapteron) from Camissonia, and by the inclusion of three previously separate genera (Calylophus, Gaura, and Stenosiphon) in Oenothera. Within the branch of the family that lacks stipules (Gongylocarpeae, Epilobieae, and Onagreae), the last two tribes form a clade that has very strong molecular support (R. A. Levin et al. 2003, 2004), but no obvious morphological synapomorphy. The clade may be defined by a cytogenetic change from the base chromosome number of x = 11 found in Circaeeae, Gongylocarpeae, and Lopezieae, to x = 18 in Epilobieae, and x = 7 in Onagreae; however, these changes could also have occurred independently. Other than the new chromosome number x = 7, the only apparent morphological synapomorphy for Onagreae alone is pollen with prominent apertural protrusions (J. Praglowski et al. 1987, 1989), a character state also found in Circaeeae (Praglowski et al. 1994). The monophyly of Onagreae has moderate (Levin et al. 2004) to strong support (V. S. Ford and L. D. Gottlieb 2007).

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