Flora of North America species comparison

Species 42 (41 in the flora).

Molecular phylogenetic analysis places a strongly monophyletic Clarkia as sister to Gayophytum and Chylismiella (R. A. Levin et al. 2004). All but one species of Clarkia are endemic to western North America; the only exception is C. tenella (Cavanilles) H. Lewis & M. E. Lewis, which occurs in Mediterranean-climate regions of Argentina and Chile. Several species of Clarkia are grown ornamentally, especially C. amoena, the so-called Godetia of horticulture, and C. unguiculata, the common garden clarkia. Both species and cultivars developed from them are used in annual border plantings or in hanging baskets. Clarkia pulchella is also commonly cultivated, especially in Europe. Clarkia has been the subject of detailed systematic and evolutionary studies for more than half a century, and there are many reports of these studies in the literature (H. Lewis and M. E. Lewis 1955; V. S. Ford and L. D. Gottlieb 2003; V. M. Eckhart et al 2004).

(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.)