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Alligator Weed

Alternanthera philoxeroides



Alligator weed is a perennial plant native to South America and often forms very dense stands or mats that make shoreline access difficult. Aquatic stems are hollow and can be single or branched. Leaves are opposite, long, elliptical or lance-shaped up to 3/4 inch wide and 5 inches long with a prominent midrib. Roots often develop at leaf nodes. Soft, whitish hairs are found in the leaf axis. Flowers are singular,  small (about 1/2 inch in diameter), white, fragrant clusters of 6 to 10 florets, borne on long branches (to 3 inches). The flowers resemble those of white clover. A single seed develops within the fruit.

This plant often forms mats in conjunction with Water-hyacinth (Eichhornia crassipes) and several species of Ludwigia. The mats can clog streams, canals, and ponds in coastal and eastern Texas.







This plant is not native to North America and it is illegal to possess or transport this species in Texas. Please report any sightings of this plant to Texas Park and Wildlife Department.