Origin:
Two species of fanwort are native to the southeastern United States, and occur throughout the southeast as native plants, and in the Pacific Northwest and the Northeast as exotic invaders.
Biology:
This perennial weed is submersed and usually is rooted, with long stems that bring the leaves to the surface, where they may be at the surface or a few inches below. Flowers occur above water. It is an extremely aggressively growing plant that may crowd out other vegetation and clog drainage ditches or canals. It grows best in quiet waterways with little water flow. Propagation is from seeds or rhizomes, as well as by vegetative parts that easily break off the parent plants. Flowering in throughout the summer.
Identification:
Foliage generally remains underwater, with leaves opposite or in whorls along the stems. The submersed leaves are divided into numerous very thin branches, while the smaller floating leaves are linear and entire, and occur near the flowers. Flowers are found above the water surface as small, whitish-yellow flowers that are inconspicuous.
Characteristicts Important to Control:
Stems and rhizomes are fragile and break off easily when the plants are disturbed, and these can will grow new plants. Attempts to dry out infested areas are not successful, as the seeds are hardy and survive desiccation. An aquatic herbicide is generally needed.
