Why are some asters no longer called “asters”
Although many gardeners, nurseries and nature-lovers may still call asters “asters”, botanists reclassified many of the plants that were once asters into other genera in the 1990's. The reason is that molecular (DNA) and morphological studies have shown that the North American asters are genetically distinct from Eurasian asters. Only recently, after years of resistance, many horticultural and botanical groups have adopted this change in their communications, so gardeners are increasingly seeing the same plant listed under both old and new names.
The taxonomic relationship between different Asteraceae is an on-going area of investigation and the classification of asters may continue to change. There are several genera that are considered variously of the Asteraceae or Compositeae families by different botanical naming authorities. For the time being, genera of North American asters include Doellingeria, Eurybia and Symphyotrichum, as well as two species still classified as asters: Aster alpinus and Aster tataricus . Of these Symphotrichum (Michaelmas daisy) contains the most species and is by far the most important name for U.S. gardeners to recognize.
Some examples of native asters from the Northeast of the U.S. are: common blue wood aster (Symphyotrichum cordifolium), New England aster (S. novae-angliae) and New York aster (S. novi-belgii).
Courtesy of the NYBG Plant Information Service