Perennial; stiff 4 sided stems are simple or branched. Leaves are opposite or whorled and have smooth edges. Small magenta flowers with 5-7 petals on tall showy spikes.
Disturbed sites, perennial and seasonal wetlands, marsh and pond edges, streambanks, cananls and ditches.
Can quickly develop into a large clump, diameter up to 5’. Can quickly adapt to environmental changes and expand its range to replace native vegetation used for ground cover, food or nesting material. Provides no cover for nesting ducks (Timmerman 1992). Recreational hunting or trapping grounds are lost, decreasing the land value of operational wetlands.