Flower:

Up to 50 small daisy-like flowers in an open branching cluster at the top of the plant. Flowers are about ¾ inch across, with 80 to 125 narrow white rays (petals) and a yellow center disk. Early heads form at the tip of the branch and nearby lateral buds, but as the season progresses, lower lateral buds also expand into heads creating a panicled cloud of the small white flowers.

Behind the flower are 2 to 4 rows of narrow bracts, covered in long flattened to slightly spreading hairs. The flower stalk is ¾ to 1 inch long and also covered in very short hairs.

Leaves and stems:

Leaves are 2 to 6 inches long, 1 to 3 inches wide, covered with sparse stiff hairs. Basal leaves are elliptic to spatula shaped, coarsely toothed with rounded tips and winged stalks, becoming stalkless, more lance-shaped and less toothed or toothless near the flower clusters. Single or multiple stems from the base are ridged and lined with sparse bristly hairs.

Fruit:

Fruit is a small nondescript seed head, the fine seed is less than 1 millimeter long, brown and nearly plumeless.

Notes:

Considered a weed by many, Annual Fleabane was one of the more weedy native species I enjoyed having invade my more formal garden in my early transitional gardening years. Some hand weeding every year was required but it never threatened to take over the garden and I wouldn't trade away the bright airy arrays of tiny white flowers in the passing summer's sun. Similar species are Prairie Fleabane (Erigeron strigosis), which is overall a smaller plant with (usually) narrower, toothless leaves, and Philadelphia Fleabane (Erigeron philadelphicus), which blooms earlier in the spring and has clasping leaves.