Amaranthaceae, the Amaranth Family
This is a perennial herb with stems that are sometimes erect, but usually creep along the soil and produce roots at the nodes. The stems can be lined with vertical rows of whitish hairs. The leaves are simple, opposite, hairless, with no teeth along the margin, narrowly oval to oblong, blunt or pointed at the tip, 2 to 4 inches long and less than an inch wide. The flowers are white, with a paper-like texture, and are borne in dense, rounded, clover-like heads in the leaf axils. The sessile flower heads are about 1/2 inch long and wide. The dry fruits, called utricles, remain attached to the flower tepals until the mature fruit is exerted beyond their tips.
This weed is found in wet disturbed areas and is a weed of rice and sugarcane fields in tropical and subtropical regions. It is possibly native to southern Asia, but is now found in tropical and subtropical regions around the world and has been introduced throughout the southeastern United States from South Carolina to Texas.
This species has been reported in Florida counties that are scattered from Escambia and Duval to Lee and Broward. It grows in wet and drier areas, including roadsides, ditches, swamps, pond banks, disturbed areas, pastures and other cultivated areas.
Six additional exotic species and two native species of Alternanthera are found in Florida, including the noxious weed A. philoxeroides, which has a stalked flower.
The seeds are dispersed by both wind and water. In addition, the plant is able to reproduce vegetatively by rooting at nodes.
This plant is an agricultural weed and is regulated as a federal noxious weed, as well as in several states, including Florida, but it is not included on the Florida Exotic Pest Plant Council (FLEPPC) list of invasive plants. This plant is classified as a terrestrial weed by the state of Florida, but it can grow as an aquatic, and is found in the aquarium trade. It is used as a vegetable in some areas of tropical Asia and has been used medicinally as well.