His dissertation was a revision of the genus "Erigeron". "Erigeron hungaricus" of the genus "Erigeron", and others. The larvae feed on "Erigeron" and "Heterotheca subaxillaris". "Erigeron glaucus" occurs in several different plant associations. Some of the endangered plants are, the Willamette daisy (Erigeron decumbens var. "Erigeron compositus" is perennial herb rarely more than tall. "Erigeron filifolius" is widespread across much of western North America. "Erigeron speciosus" grows on in prairies and in open coniferous forests. Erigeron oreades is an Asian species of flowering plants in the daisy family. Erigeron aurantiacus is an Asian species of flowering plants in the daisy family. "Erigeron elegantulus" grows on the rocky volcanic soils of the region. Erigeron compositus is an Arctic and alpine species of fleabane in the daisy family. The genera "Arnica", "Castilleja", "Erigeron", and "Lomatium" have their major center of diversity here. "Erigeron vetensis " grows in dry, open sites in openings in conifer forests. It can easily be confused with "Erigeron canadensis", which grows taller, and "C. albida".