A genus of about 70 species, herbs, of temperate and subtropical areas. Of our species, A. neglecta, A. solitaria, A. virginica, and A. plantaginifolia are sexual diploids. A. parlinii is of multiple hybrid origin, includes sexual and asexual populations, and is derived from A. plantaginifolia, A. solitaria, and A. racemosa. A. howellii is strictly asexual, and is derived from A. plantaginifolia, A. racemosa, A. virginica, and A. neglecta (Bayer 1985). For reasons discussed in Bayer & Stebbins (1982) and parallel to those applied in this work to allopolyploid taxa in Eupatorium, the treatment of Bayer (1985) and Bayer & Stebbins (1993, 1982) is preferable to Cronquist's treatments, used in most of the floras covering or approaching our area. Much remains to be learned about the relative habitats and distributions of the various taxa in our area.
Ref: Arriagada (1998); Bayer (1984); Bayer (1985); Bayer (2006) In Flora of North America Editorial Committee (2006a); Bayer & Stebbins (1982); Bayer & Stebbins (1987); Bayer & Stebbins (1993); Cronquist (1980). Show full citations.