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

Appearance
Lythrum salicaria is a tall, multistemmed (30-50 per plant), perennial forb that can grow up to 10 ft. (3 m) in height.
Foliage
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.
Flowers
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.
Fruit
Fruits are capsules that are enclosed in the hairy sepals and contain several reddish brown seeds.
Ecological Threat
Lythrum salicaria is a serious invader of many types of wetlands, including wet meadows, prairie potholes, river and stream banks, lake shores, tidal and nontidal marshes, and ditches. It can quickly form dense stands that completely dominate the area excluding native vegetation. This plant can spread very rapidly due to its prolific seed production; each plant can produce up to 2.5 million seeds per year. It can also hybridize with native loosestrife species, potentially depleting the native species gene pool. Lythrum salicaria is native to Europe and Asia. It was first introduced into North America in the early 1800s for ornamental and medicinal purposes.

Identification, Biology, Control and Management Resources