Origin:
Native to North America and found in all states east of the Rocky Mountains, as well as along the Pacific Coast states. It also is found in Hawaii, eastern Canada, the West Indies, and in Mexico through Central America.
Biology:
A large summer annual weed that reproduces from seeds. There is a large, strong taproot as well as a number of thick lateral roots for support. Plants may reach as tall as 8 feet, and foliage produces an unpleasant odor when it is crushed. This weed may be found in almost any disturbed site, along roadsides, and in pastures and open fields. Seeds have a number of long hairs at their top that aid in wind dispersal.
Identification:
Plants are erect, with a thick, fibrous main stem that may be smooth to slightly hairy. The leaves are alternate to spiraling along the stem, and along the upper stem the leaves have clasping bases. The leaf is long and lance-shaped, with variable margins that may be lobed or simply deeply toothed. Flower heads occur at the ends of the many branches at the top of the plant, and the flowers are white to pink.
Characteristicts Important to Control:
Physical removal of single plants is effective. When found in turf most members of the sunflower family can be effectively controlled with a selective broadleaf herbicide. Prevention of seed germination can be accomplished with a pre-emergent herbicide.
