Horseweed (Marestail)

Scientific Name - Conyza canadensis (L.) Cronq.
Family - Compositae

Tall-growing summer or winter annual with bristly hairy stems. Leaves alternate, lack petioles, linear to oblanceolate. Leaf margins often toothed; lower margins with long hairs. Flowers in numerous, small heads on branches in the upper portion of the plant. Reproduces by seed. Found throughout the United States. Also occurs in Quebec, Ontario, Mexico, Central and South America, and Europe.