LOWER
PLATTE
WEED MANAGEMENT AREA
Purple Loosestrife
Lythrum salicaria L.& Lythrum virgatum L.
including any cultivars and hybrids
Purple Loosestrife was designated as Nebraska's seventh noxious weed on January 1, 2001.
Scattered across Nebraska in marshes, along rivers, ditches, and wet meadows. The largest infestations are along the Platte River in Central Nebraska, and along the Missouri River
above Gavins Point Dam. Other infestations can be found along the Niobrara River and in ornamental settings.
Purple Loosestrife is rapidly and aggressively spreading and has been placed on the noxious
weed list in some north central states. Several varieties have been developed which can
cross with wild types and produce viable seed. It is extremely difficult to control, and
concentrated efforts should be made to keep it from spreading.
Before the LPWMA was formed, a successful group effort to remove ornamental plantings
by the way of a two year Statewide Exchange Program. This effort resulted in the removal
of nearly
10,000 plants from landowner landscapes across Nebraska. The removal of these
plants meant that 10,000 potential seed sources were eliminated. Seeds from these plants
have been found to wash off of the plants and find their way to nearby creeks, ponds, and
lakes.
The LPWMA was formed to address the "wild" infestations of purple loosestrife that can be
found in the Lower Platte River drainage area. Since it's formation, the LPWMA has surveyed
for infestations in the drainage area and found that infestations can be found on the Platte River
from near Columbus, Ne. to it's mouth at the Missouri River.
Since the formation of the weed management area, nearly 100 miles of the Platte River has been
surveyed. With the help of a grant from the National Fish & Wildlife Foundation Pulling Together
Initiative, nearly 75% of the infestations have been treated by chemical or have had insects (see biocontrol project) released on them. Continued monitoring and control is being planned for upcoming years.
Plant Facts
Common Name: Purple Loosestrife (purple lythrum, spiked loosestife)
Scientifice Name: Lythrum salicaria L.
Growth Form: Forb
Life Span: Perennial
Origin: Eurasia and Africa
Flowering Dates: July-September
Reproduction: Seeds and rhizomes
Height: 0.4-2.5 m (1.3-8 ft)
Inflorescence: Cymules arranged in spikes, terminal
Flowers: Rose-purple corolla (up to 2 cm across), petals 6 (5-7), crinkled; tube cylindrical (4-6 mm long), greenish; calyx lobes 6; stamens 12
Fruit: Capsule (4-7 mm in diameter), 2-celled, many-seeded
Seed: Ovoid ( 1 mm long or less)
Leaves: Opposite or in whorls; blades simple, lanceolate (2-11 cm long, 5-15 mm wide), tip sharply pointed, base rounded or heart-shaped, margins entire, surfaces pubescent; sessile
Stems: Erect, 4-angled, hairless to pubescent, not highly branched, usually from a woody base
Underground: Rhizomes, short; taproot
Where Found: Scattered across Nebraska in marshes, along rivers, ditches, and wet meadows. The largest infestations are along the Platte River in Central Nebraska, and along the Missouri River above Gavins Point Dam.
Uses and Values: Purple Loosestrife is an escaped ornamental. It is an excellant honey plant
Poisoning: None
Other: Purple Loosestrife is rapidly and aggressively spreading and has been placed on the noxious weed list in some north central states. Several varieties have been developed which can cross with wild types and produce viable seed. It is extremely difficult to control, and concentrated efforts should be made to keep it from spreading.
Similar Species: Winged Loostrife (Lythrum alatum Pursh) and California Loosestrife (Lythrum californicum T.&G.) are native species similar in appearance. They differ from Purple Loosestrife by having solitary or paired flowers in the leaf axils rather than many flowers in terminal spikes and 6-8 stamens rather than 12. Winged Loosestrife leaves are gray-green and often somewhat fleshy. Californa Loosestrife has green, membranaceous leaves.
Information and Pictures - Courtesy of the Nebraska Department of Agriculture