Erigeron annuus is an annual herb, 30-150 cm tall, from fibrous roots (Yatskievych 2006), stem leafy, usually hairy, often branched above.
Leaves alternate, basal leaves 1.5-8 cm long, 0.3-2 cm wide, long stalked, lance- to egg-shaped stem leaves broadly lance-shaped, narrowed to base, sessile (no stalk) but not clasping stem, surfaces hairy, margins usually toothed, except uppermost.
Flowers in radiate heads, rays white (rarely pink), numerous, 80-125, very slender, 0.4-1 cm long, to 0.1 cm wide (much thinner and more numerous than ray flowers in Aster), disk flowers yellow, 0.2 cm long; bracteate base of flower head 0.3–0.5 cm tall, 0.6–1.2 cm wide, bracts in 2-3 rows, the longest 0.5-0.6 cm long, 0.1 cm wide, often with a row of small, outer bracts (Yatskievych 2006; Flora of North America 1993+), finely hairy; blooms and fruits June-Oct.; inflorescence of flowers on long stalks both terminal and axillary, flower buds hairy, in dense clusters at branch tips, reproduction obligately asexual (apomictic), (Kenny 1996).
Fruit dry, 1-seeded, plumed achenes, 0.1 cm long, wind dispersed; germination in early autumn, overwintering as rosettes (Kenny 1996).
Wetland status: FACU.
Frequency in NYC: Frequent.
Habitat: Open, disturbed areas, meadows, roadsides, fill.