purple loosestrife USDA PLANTS SYMBOL: LYSA2
Lythrum salicaria L.
Synonym(s): purple lythrum, rainbow weed, salicaire, spiked loosestrife

Purple loosestrife is a tall, multi-stemmed (30-50 per plant), perennial forb that can grow up to 10 ft. (3 m) in height. The opposite or whorled leaves are dark-green, lance-shaped, sessile, 1.5-4 in. (3.8-10.2 cm) long and round or heart-shaped at the base. Flowering occurs in July to October, when pink to purplish flowers develop in 4-16 in. (10.2-40.6 cm) long spikes at the tops of the stems. Flowers have 5-7 petals and twice as many stamens as petals. Fruits are capsules that are enclosed in the hairy sepals. Purple loosestrife is a serious invader of many types of wetlands, including wet meadows, prairie potholes, river and stream banks, lake shores, tidal and non-tidal marshes, and ditches. It can quickly form dense stands that displace native vegetation. Purple loosestrife can spread very rapidly due to its prolific seed production; one plant can produce as many as 2 million seeds per year. Purple loosestrife is native to Europe and Asia. It was first introduced into North America in the early 1800s for ornamental and medicinal purposes. It has also been used as a nectar plant for bee-keeping.

Identification, Biology, Control and Management Resources