One identifying characteristic of erigeron glabellus
is the large number of ray florets; flower heads have between 125 to 175, and they overlap so that there are no gaps between. Rays are a quarter to a third of an inch in length, about the same as the diameter of the group of disc florets at the center. The phyllaries are in 3 to 4 rows, hairy, but not glandular. The stem and leaves may be lacking in hairs, or have a light covering; they are generally less hairy than some similar species, hence the common name of smooth fleabane. Stems are topped by between 1 and 15 flower heads. Leaves grow mostly around the base; those up the stem are fewer in number, shorter and narrower.