New taxa in Oenothera (Onagraceae)

A new species, three new sections, and one new subsection of Oenothera are described and a new combination in O. flava is made here so that the names will be available. Oenothera coryi (sect. Megapterium), which ranges from north-central Texas to the southern part of the panhandle, is described. The combination O. flava subsp. taraxacoides (sect. Lavauxia) is made for large-flowered, modally outcrossing populations of O. flava from three disjunct areas: 1) Mogollon Plateau, Arizona to Catron Co., New Mexico; 2) Sacramento Mountains and Sierra Blanca in southeastern New Mexico; and 3) Sierra Madre Occidental from Chihuahua to Durango, Mexico. As part of a genus-wide reevaluation of the infrageneric classification, three new sections, sect. Ravenia, sect. Eremia, and sect. Contortae, are proposed for species formerly included in subg. Pachylophus, which is no longer recognized, and subsect. Australis is described for the two white-flowered South American species of sect. Lavauxia.