Purple Loosestrife (State designated weed)

Purple Loosestrife (State designated weed)

  • Lythrum salicaria
  • Lythraceae (Loosestrife family)

Purple loosestrife is an introduced European ornamental that infests aquatic sites such as streambanks or shorelines of shallow ponds. Infestations can become dense and impede water flow in canals and ditches. Reports of reduced habitat for wildlife use are common.

Growth Habit: A rhizomatous perennial with upright stems, often growing 6 to 8 feet tall, usually associated with moist or marshy sites.

Leaves: Simple, entire, and opposite or whorled.

Flowers: Rose-purple having five to seven petals arranged in long, vertical, showy racemes. Flowering continues throughout summer producing 2 to 3 million tiny seeds per plant in trumpet-shaped seed pods.

Other: Also called purple lythrum, it has steadily infested wetlands since its introduction in the early 1900s, crowding out other native species.

Status: State Designated Noxious Weed, Category 1 Fremont County. Rare. No tolerance, with a goal of early detection and eradication.

Control: Chemical controls are effective. FCWP offers a 40 percent Cost Share on chemicals for controlling this species. Contact your local weed and pest office if you find this species in Fremont County.

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