Northern Prairie Wildlife Research Center
Purple Loosestrife (Lythrum salicaria)
- Family: Loosestrife (Lythraceae)
- Flowering: June-September.
- Field Marks: This tall, coarse perennial is distinguished by its densely flowered terminal purple spikes, its flowers with 6 free petals, its opposite hairy leaves, and its hairy stems.
- Habitat: Marshes, margins of ponds, lakes, rivers, and streams.
- Habit: Coarse perennial from a thickened rootstock.
- Stems: 1-several erect, branched or unbranched, usually hairy, up to 3 1/2 feet tall.
- Leaves: Opposite or sometimes in whorls of 3, simple, linear to lanceolate to oblong, pointed at the tip, rounded at the sessile base, without teeth, usually hairy, the largest up to 4 inches long.
- Flowers: Crowded in terminal spikes up to 15 inches long, purple, the flowers subtended by green, leafy bracts.
- Sepals: Usually 6, green, united below to form a tube that is usually shorter than the petals, usually somewhat hairy.
- Petals: Usually 6, purple, free from each other, up to 1/2 inch long.
- Stamens: Usually 6.
- Pistils: Ovary superior.
- Fruits: Capsules slightly longer than broad, containing numerous minute seeds.
- Notes: This species, a native of Europe, has become a very aggressive invader of wetlands, eventually choking out much of the native vegetation.
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