Erect, often in large expanding clumps. Stems branched or not, covered with gray hair. Leaves opposite, whorled or alternate above, sessile, lance-shaped, with pointed tip, 2–6 in. long, hairy. Inflorescence consists of a spike at top with egg-shaped bracts, sessile flowers. Flowers wrinkled, purple or red-purple; petals 5–7, about 1/2 in. long; stamens more or less 12; styles 3 distinct lengths. Grows worldwide in ditches, margins of streams and ponds, marshy places, at low elevations. Considered one of the most noxious aquatic weeds in North America, it takes over wetlands and displaces native plants.
- Rarity: Common
- Flowering Time: All Summer
- Life Cycle: Perennial
- Height: 2--6 feet
- Habitat: Meadow, Coastal, Bog/Fen/Wetland
- Found In: Siskiyous, West Gorge, Steens, Olympic Np
- Native: No