Flowerheads of erigeron compositus
consist of several dozen yellow disc florets surrounded by a ring of 20 to 60 ray florets, which may be any color from pure white to pink to purple. The corollas of the ray florets are around a third of an inch long, and somewhat variable in width. Occasionally the ray florets are absent. Phyllaries are in two or three rows, colored green or purple, and covered in spreading white hairs. Plants produce one flowerhead per stem.
The red or green stems are unbranched, short, and hairy, and they bear leaves mostly at the base; the few stem leaves are much reduced in size, Basal leaves are divided two or three times, sometimes four times, into small, linear lobes, usually hairy; the finely divided foliage is one feature that distinguishes this species from other fleabanes. Plants spread through rhizomes, forming small clumps.