Lythrum salicaria Linnaeus
Synonym(s): purple lythrum, rainbow weed, salicaire, spiked loosestrife
This plant grows 3-7 feet tall and puts up several spikes of purple flowers in June-July. The leaves are opposite and the stems are square. Purple loosestrife spreads aggressively by seed and by rhizome. Even “sterile” cultivars can still produce viable seed. Note – it is illegal to buy, sell, or plant purple loosestrife in Indiana (IC 14-24-12-7). Purple loosestrife invades wetlands in northern Indiana, forming pure stands that choke out native vegetation. This eliminates food and cover for many wildlife species, which are dependent on a diverse mixture of native species to survive.
In 100 Years of Change in the Distribution of Common Indiana Weeds by William and Edith Overlease (2002) reported that purple loosestrife was not found in Indiana in 1899 (Coulter’s Catalogue of Indiana Plants); however, in 1940 (Deam’s Flora), purple loosestrife was reported in Clark, Harrison, Jefferson, and Perry counties but no herbarium specimens were taken. In Overlease (2002) reported purple loosestrife in the following 35 counties in Indiana: Blackford, Brown, Cass, Clark, DeKalb, Dubois, Elkhart, Floyd, Fulton, Hamilton, Harrison, Jackson, Jefferson, Kosciusko, LaGrange, Lake, La Porte, Madison, Marshall, Monroe, Noble, Perry, Porter, Pulaski, Putnam, Ripley, St. Joseph, Shelby, Starke, Steuben, Tipton, White, and Whitley. It has also been reported in Marion and Scott counties.