Description A coarse weed with erect bristly-haired stem that has branching clusters of small, cup-like, greenish-white flower heads arising from upper leaf axils. The minute white rays do not spread and thus are not showy; the numerous disk flowers are yellow.
Flowers: heads less than 1/4" (2.5-10 cm) long, dark green, linear to narrow lanceolate, hairy, usually slightly toothed.
Fruit: tiny, 1-seeded, with numerous bristles that aid seed dispersal.
Height: 1-7' (30-210 cm).

Flower July-November.

Habitat Fields, roadsides, and waste places.

Range Throughout North America, except parts of far north.

Discussion An annual that thrives on bare soil, Horseweed is soon crowded out as perennials become established. Originally a North American plant, it has spread to Europe, where it colonizes open disturbed sites. Indians and early settlers used a preparation of its leaves to treat dysentery and sore throat.