Purple Loosestrife or Lythrum (Lythrum salicaria, L. virgatum, and any hybrid crosses thereof)

Status:

Listed Noxious Weed In Montana & North Dakota

History:

First Montana Specimen Collected 1

County:

Toole

Year:

1980

“Purple Loosestrife (Lythrum salicaria) is a wetland plant from Europe and Asia. It was introduced into the east coast of North America in the 1800s. First spreading along roads, canals and drainage ditches, and then later distributed as an ornamental, this exotic plant is in 40 states and all Canadian border provinces.”. (GLIN)

Habitat:

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 to 7 petals and numerous stamens, in long, vertical recemes.

Roots:

Large fleshy, adapted to aquatic sites.

Seeds:

Average 900 seed capsules per plant with 120 flat thin walled seeds per capsule.

Other Notes:

“Due to the quantity of seed produced by Purple Loosestrife it can quickly take over
wetland habitat. These stands create a monoculture that can be
impenetrable even by boats. Efforts to create better wildlife habitat, by
thinning cattails, have resulted in the creation of the perfect pathway
for Purple Loosestrife invasion.”(GLIN, 24)