Origin:
Native to the eastern United States, but now spread throughout the country, most commonly found in the southern U.S.
Biology:
An annual that sometimes will act as a biennial. It is found primarily in very wet locations such as along the banks of rivers or canals, as well as such places that will dry out later in the season. It also is a pest weed in many crop environments where irrigation is heavy. Propagation is from seeds, although stems will root at the nodes.
Identification:
Mature plants have stems that may grow to 2 feet long, but in general they are weak and tend to lay along the soil, branching up at the terminal ends and rising to form a fairly bushy appearance in larger plants. Stems will root at the nodes where they contact the soil. Both leaves and stems have a rough texture due to the short, rough hairs on them. Leaves are opposite and are long and thing, usually without stalks. The leaf margins have widely spaced teeth that point toward the tip. Flower heads are less than one half inch across and are borne singly on stalks that arise from the base of the upper leaves or in the fork of stem branches. The disc flowers are green and the ray flowers surrounding them are short and white and notched at the tip.
Characteristicts Important to Control:
Very wet areas are preferred by this plant. Physical removal is effective.
