PURPLE LOOSESTRIFE - Lythrum salicaria L.

Lythraceae - (Loosestrife family)

Purple Loosestrife is easily one of the most beautiful and also one of the most invasive weeds in Wyoming and much of the USA.  It is grown as an ornamental known as Lythrum, but with as many as 2-3 million seeds per plant it has escaped to infest moist, marshy or wet areas as canals, ditches, or lake edges, and has steadily infringed these areas since its introduction in the early 1900’s crowding out other native species.  There is very little natural control for loosestrife as it is not nutritious to wildlife or livestock.

Bright green, lance shaped leaves with smooth edges spring from seed soon followed by stem growth.

The 4 to 10 ft. reddish fibrous stems grow from woody perennial roots which interlace to form dense woody mats, from creeping horizontal roots and from seed. Leaves are opposite or grow around the stem in threes.  The leaves grow very close to the stem and attach by the light colored mid vein, these connections may also give rise to smaller branching stems.  The leaves grow smaller and fewer upward on the plant.
The upper 1/3 of the stem is a spike of purple flowers.  Each flower grows from a trumpet shaped form from which 5-7 purple petals, and showy stamens protrude  The flowering continues through out the summer producing tiny seeds in the trumpet shaped seed pod.

The following is courtesy of Weeds of the West:
A rhizomatous perennial with erect stems, often growing 6 to 8 feet tall, usually associated with moist or marshy sites. Leaves are simple, entire, and opposite or whorled. Rose-purple flowers having 5 to 7 petals are arranged in long vertical racemes.

Purple loosestrife, is an introduced European Ornamental species that often escapes to 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.

Non-standard name: purple lythrum.

(Courtesy of Weeds of the West)

No identified infestations in Fremont County.