Purple loosestrife (Lythrum salicaria)
Keys to ID:
- Showy pinkish-violet flowers bloom in long, vertical spike.
- Smooth, lance-shaped leaves.
- Four-sided stems.
Identification:
- Lifecycle: Perennial
- Growth Form: Forb or woody sub-shrub
- Flower: Pinkish-violet flowers with 5 to 7 petals arranged in vertical spike, usually July to mid-September.
- Seeds/Fruit: Fruits are many-seeded capsules; seeds are small and ovid.
- Leaves: Simple, entire, either opposite or whorled.
- Stems: Annual stems arise from a perennial rootstock. Stems are erect, and 1.5 to 8 feet tall. Plants become tall and bushy as the rootstock matures.
- Roots: Short rhizomes and taproot Propagation: Primarily by seed, as it produces up to a million seeds per plant and can have high levels of viability in seeds. Can also spread vegetatively from stem cuttings (Belliston et al. 2004, USDA 2006).
- Other: sometimes confused with Fireweed (Epilobium spp.) which have four-petaled flowers.
Control:
Mech: Hand removal, prior to seed set; digging to remove entire rootstalk. Flower stalks must be cut, bagged, and disposed of properly. Seeds may be viable even after spraying, so removal and bagging of flower stalks is key.