Ludwigia (Group), referring to clustered stands of Ludwigia peruviana, describes the plant as it appears when growing in dense, interconnected colonies along wetland edges. In this form, Ludwigia peruviana becomes a tall, thicket-forming presence with multiple stems rising together above shallow water or saturated soils. The collective growth creates a structural mass, shading out lower vegetation and shaping the character of marshes, canals, and slow-moving rivers.

Grouped Ludwigia peruviana spreads largely through vegetative expansion, allowing entire patches to advance as a unified block. This form is ecologically influential, altering hydrology, restricting native species, and creating pockets of habitat for birds and insects that rely on dense shrub-like wetlands. In many regions, grouped stands of Ludwigia peruviana are considered aggressive due to the way they dominate disturbed environments.