Alturas Field Office

Noxious Weeds


Purple Loosestrife   (Lythrum salicaria)
Loosestrife Family (Lythraceae)


Purple Loosestrife
University of Idaho


Next Plant
Next Plant Arrow


Description: Rhizomatous perennial with erect stems, 2 to 6 feet. Leaves lance-shaped, simple, entire, and opposite or whorled. Flowers rose-purple, with 5 to 7 petals, less than 1/2 inch long, arranged spike-like and terminal on the stem.

Habitat: Native to Europe. Usually associated with moist or marshy sites, ponds, meadows, ditches, and streambanks. Infestations can become dense and impede water flow in canals and ditches. Introduced and cultivated as an ornamental.

Distribution: The largest known infestation of Purple loosestrife in northeastern California is north of McArthur (Shasta County). There are smaller sites at Tulelake and the Lower Klamath National Wildlife Refuge (Siskiyou County) and near Reno, Nevada along the Truckee River (Washoe County).

Flowering Period: August to September.