A genus of mostly perennial herbs in which the leaves are simple and spirally arranged, the flower heads have imbricate bracts and flat, naked receptacles; ray florets, usually present, are white, blue, or red, but never yellow but the disc florets are yellow. The achenes are flattened and smooth with a pappus of short, bristly hairs. Many N. American species are cultivated as Michaelmas daisies and have become naturalized in Europe and elsewhere. There are about 250 species, mostly northern temperate.
Subjects: Plant Sciences and Forestry.