The Mission of the Yellowstone County Weed Department is to assist the public, private, and other government agencies to manage and control existing noxious weed infestations as well as to prevent new invasive species from infesting Yellowstone County.

Purple LoosestrifeLythrum salicaria L.

Loosestrife family - Lythraceae

Photo from Montana Weed Control Association

Stalk

Stalk

Leaf

Plant

Bloom

Mature

Photos from Montana Weed Control Association

Video Supplied By Montana Weed Control Association

Attribute	Description
Growth Habit	Perennial, erect to 8 feet tall, associated with moist or marshy areas.
Leaves	Simple, lance-shaped, smooth margins, opposite or whorled.
Stem	Branched, terminating in flowering stalks.
Flower	Rose-purple flowers having 5-7 petals and numerous stamen, in long, vertical recemes.
Roots	Large, fleshy, adapted to aquatic sites.
Seeds	Oval, 1mm long seeds develop in capsules that burst when mature. More than 2 million seeds can be produced by an average sized plant.
Reproduction	Primarily by seeds, but can spread through cut stems and fragmented roots.
Habitat	Aquatic sites such as marshy areas, streams, and stream banks, ponds, irrigation canals and ditches support the worst infestations.
Biological Controls	Black-margined loosestrife beetle (Galerucella calmariensis), Golden loosestrife beetle (Galerucella pusilla), Loosestrife root weevil (Hylobius transversovittatus).
Herbicides	None used in Yellowstone County at this time.