Introduced from South America, likely as an ornamental plant, and now established along the west coast of the U.S., and from Texas and Missouri east to Florida and north to New York along the east coast.
A semiaquatic plant found growing in very wet sites along the banks of creeks, ditches, irrigation canals, or lake margins, or in seasonally empty creek beds. This is a perennial weed that grows either floating or upright on strong stems, forming thick stands that crowd out other vegetation. Reproduction is from seeds, foliage dies back in the winter with new growth from the roots, and spread can be from rhizomes.
Mature plants can be over 3 feet in height, with numerous stems that root at the nodes, as well as creeping rhizomes. Leaves are lance-shaped and wider at their outer end than the inner end. Veins are distinctly lighter in color than the dark green leaf. Flowers are bright yellow and showy, with 5 broadly opened petals, and growing on stalks along the upper ends of the stems.
Characteristicts Important to Control:
A systemic herbicide labeled for the site to be treated will be necessary to control this perennial weed, with physical removal of dead vegetation possibly needed to clear a waterway.