Quick facts
Purple loosestrife is a prohibited invasive species. Purple loosetrife is on the Control noxious weed list meaning you must prevent the spread of this plant.
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Purple loosestrife can invade many wetland types including wet meadows, stream banks, pond or lake edges and ditches.
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Populations can expand quickly and form dense stands that crowd out native vegetation.
- Purple loosestrife should be reported.
See the Minnesota Department of Natural Resources recommendations for reporting invasive species.
How to identify purple loosestrife
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Purple loosestrife (Lythrum salicaria) is a perennial herbaceous plant with bushy appearance.
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Can grow three to seven feet tall and will have multiple stems growing from a single rootstock.
Stem
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Stiff, typically square shaped.
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Can have up to six sides, often branching.
Leaves
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Opposite or whorled.
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Lance shaped with smooth edges
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Stalkless.
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Can be downy.
Flowers
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Purple-pink flowers bloom in tall spikes for most of the summer months.
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Multiple rings of flowers bloom at once from the bottom of the spike to the top.
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Flowers typically have six petals.
Seeds
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Tiny, with up to 300,000 seeds produced per stem each year.
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Seeds are viable for up to 20 years.
Roots
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Large, woody taproot with rapidly extending, fibrous rhizomes.
Reviewed in 2019