A Taxonomic Revision of Chilopsis (Bignoniaceae)

The genus Chilopsis contains one species, C. linearis, with two subspecies: subsp. linearis of the Chihuahuan Desert characterized by erect, straight leaves, and subsp. arcuata of the Sonoran and Mojave deserts with longer, arcuate leaves and other distinguishing characteristics. Populations of subsp. linearis east of the Sierra Madre Oriental in eastern Mexico have woolly stems and are described as a new variety, tomenticaulis. Relationships between Chilopsis and Catalpa are discussed and data are presented supporting continued recognition of Chilopsis as a distinct genus