Unwanted Organism, National Pest Plant Accord
- Scientific Name: Lythrum salicaria
- Origin: Native to Europe, Asia and Australia
- Type: Weed
- Plant Life-form Type: Marginal erect/tall
- Taxonomy: L.
- Presence: Locally naturalised, especially in Horowhenua and Canterbury, first record 1958
- Habitat: Lake margins and other wetlands
- Notes: Major potential problem in still water bodies and wetlands, a major weed in North America.
- Propagation: Seed or vegetative fragments. Water dispersed, also deliberate planting
- Features: Tall emergent perennial herb. Normally 60-100 cm tall, but can grow taller. Purple flowers in dense terminal spikes. Stems are angled (4-6 sided). The stalkless leaves can be opposite, often with alternating pairs at 90 degree angles, or sometimes in whorls of 3 near the base. The upper leaves and floral bracts can be alternate. The leaves are 5-12 cm long, wider and rounded or heart-shaped at the base. Leaf shape varies from lanceolate to narrowly oblong. Leaf sometimes covered with fine hairs.
- Source: TIFBIS
- Regional: Regional Pest Management Strategy: AUK, BOP, MWT, NTL, STL, NSN/TAS, MBH, WKO, WGN.