A pretty aquatic flower, BUT... read this description from the Texas A&M aquatic plants data base:

Alternanthera philoxeroides

Non-Native

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. Often roots develop at leaf nodes. Soft, whitish hairs are found in the leaf axis. Single flowers are 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.

Submerged portions of all aquatic plants provide habitats for many micro and macro invertebrates. These invertebrates in turn are used as food by fish and other wildlife species (e.g. amphibians, reptiles, ducks, etc.). After aquatic plants die, their decomposition by bacteria and fungi provides food (called "detritus") for many aquatic invertebrates. Alligator weed has no known direct food value to wildlife and since it is a non-native should not be spread.

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 ( howard.elder@tpwd.state.tx.us )

Duly reported!