Scientific name: Lythrum salicaria
What Is It?
Purple loosestrife is a tall, perennial wetland plant with reddish-purple flowers, which may be found in sunny wetlands, wet meadows, river and stream banks, ponds edges, reservoirs, and ditches. It is native to Europe and Asia, and is responsible for a considerable amount of the degradation to wetlands throughout the United States.
Is It Here Yet?
Yes, purple loosestrife has been documented throughout Washington.
Why Should I Care?
Purple loosestrife forms dense stands that outcompete native plants for space, light, and pollinators, and provide poor habitat for waterfowl. It alters the structure and function of wetlands, clogs waterways and irrigation system, affects rice and other agricultural production, and reduces livestock forage quality.
How Can We Stop It?
Remove any plants from gardens to reduce seed sources and do not plant purple loosestrife. Purple loosestrife is listed as a Class B Noxious Weed in Washington, meaning it is designated for control in certain state regions.
What Are Its Characteristics?
- May grow up to 6 feet tall and 4-5 feet wide.
- Stems are square and a plant may have more than 30 stems.
- Small reddish-purple flowers grow in dense, showy spikes at the top of each stem.
- Leaves are opposite, hairy, and lance-shaped.
How Do I Distinguish It From Native Species?
- Fireweed, which has much larger flowers, alternate leaves, and does not grow in wetlands.
- Spirea, which has flowers arranged in clusters and oblong, alternate leaves.
- Native primrose loosestrifes are yellow-flowered.
- Native hyssop loosestrifes are shorter with white to rose petals.