Growth Habit:  Perennial, erect to 8 feet tall, associated with moist or
marshy areas.

Leaves:  Simple, lance-shaped, smooth margins, opposite or whorled.

Stems:  Branched, terminating in flowering stalks.

Flowers:  Rose-purple flowers having 5 to 7 petals and numerous
stamens, in long, vertical recemes.

Roots:  Large, fleshy, adapted to aquatic sites.

Other:  Dense infestations can impede water flow in canals and
ditches.