Purple Loosestrife

Other Common Names: spiked loosestrife

(Lythrum salicaria)


Purple Loosestrife has woody, square stems with purple flowers at the ends.


Purple loosestrife stems are four to ten feet tall, hairy, woody, and angled (four to six sides). Leaves are green and sword shaped with a round or heart shape at the base and are whorled or paired around the stems. Flowers are pinkish purple with five to seven narrow petals around a yellow center. There are many flowers along the top six to 12 inches of the flower spikes. Every purple loosestrife plant can produce as many as 2.7 million seeds each year. Purple loosestrife blooms July through September. Because flowers bloom gradually on the stalk, seeds are produced and released for multiple weeks. The seeds are as small as grains of sand and thus easily spread by wind, water, animals, and humans. Loosestrife seeds often germinate right away, but they can lay dormant for multiple years before they sprout.


Purple loosestrife looks like native fireweed and blue vervain, which are beneficial wetland plants. Purple loosestrife grows aggressively and can crowd out native vegetation.


Purple loosestrife can be found across the United States.


seeds, rhizomes