Fall Tansyaster (Dieteria asteroides Torr.)

Also classified as Machaeranthera asteroides (Torr.) Greene.

Although Machaeranthera asteroides (Torr.) Greene is listed by BONAP and POWO as a synonym of the variety Dieteria asteroides var. asteroides, denoting that the names refer to the name type specimens, and not the whole species Dieteria asteroides, this convention is misleading as there is a one-to-one correspondence between the two species names (i.e. the species was simply moved to a different genus), whereas the variety refers to a more limited population, as the species also includes two other varieties, which occur in regions where the first does not. The relationship between the "synonyms" is thus one of containment. This is one of many cases where accepted conventions in plant taxonomy obfuscate, rather than clarify, the relationships between populations being referred to by scientific names.