Native to the eastern United States, but also an introduced exotic species in Hawaii.
This annual weed can be found in many roadside habitats and along moist ditchbanks. The foliage exudes a pungent smell when crushed, and has been used for both medicinal purposes as well as an insect repellent. Propagation is by seeds that are easily wind dispersed.
Mature plants can be several feet tall, with a central stem and numerous branches. Stems and leaves are sparsely hairy. Leaves are lance-shaped and up to 5 inches long with pointed tips and toothed margins. Flowers occur in loose clusters at the ends of the stems, and are violet to pink in color.
Characteristicts Important to Control:
Physical removal is possible for individual plants. Moisture control will reduce the habitat favorable to this plant.