Ludwigia palustris

Calyx segments (sepals) broadly triangular. Flowers typically sessile in the axils of leaves. Stems red, and leaves tapering down petiole to stem (cuneate). Sometimes mistaken for alligator weed, which has thicker leaves and is more erect, not usually rooting at the nodes. The stems of alligator weed are hollow and there are small tufts of hair in the axils of the leaves. 4 green sepals. No petals. Fruit <0.5" with green stripes. Grows sprawled on ground.

Marsh seedbox is found in wet places such as ponds, streams, and marshes throughout Louisiana and east and south-central Texas.

Creeping over mudflats and partly floating in shallow water, marshes, ditches, and shallow pools, lakes and slow streams, moist depressions.