Purple Loosestrife

Purple loosestrife Lythrum salicaria

 

 

Where did purple loosestrife come from?

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    Purple loosestrife is an invasive wetland perennial from Europe and Asia.

     

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    Introduced in the early 1800s to North America via ship ballast, as a medicinal herb, and ornamental plant.

     

What does purple loosestrife look like?

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    Loosestrife plants grow from four to ten feet high, depending upon conditions, and produce a showy display of magenta-colored flower spikes throughout much of the summer Purple loosestrife is an erect perennial herb, with a square, woody stem and opposite or whorled leaves.

     

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    Flowers have five to seven petals.

     

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    Leaves are lance-shaped, stalkless, and heart-shaped or rounded at the base.

     

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    Mature plants can have from 30 to 50 stems arising from a single rootstock.

     

Why is purple loosestrife a problem?

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    Each plant may produce over one million seeds, which can remain viable for several years.

     

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    Seeds can be moved by water, vehicles, and wildlife.

     

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    Loosestrife often spreads to additional wetland sites.

     

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    Loosestrife restricts native wetland plant species, including some federally endangered orchids, and reduces habitat for waterfowl.

     

How do we control purple loosestrife?

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    Purple loosestrife cannot be transported into or within the State of Kansas.

     

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    Small infestations of young purple loosestrife plants may be pulled by hand, preferably before seed set.

     

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    For older plants, spot treating with a herbicide is recommended.

     

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    These herbicides may be most effective when applied late in the season when plants are preparing for dormancy. However, it may be best to do a mid-summer and a late season treatment, to reduce the amount of seed produced.

     

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    Research is currently being conducted to determine possible control by insects.

     

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    Contact your local Kansas Department of Agriculture office for more information.

     

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    Early detection of isolated populations may help prevent their spread. Your help to report new sightings and to prevent their spread is vital.

     

What do I do if I find purple loosestrife?

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Purple Loosestrife links:

Kansas Department of Agriculture-purple loosestrife

USDA Plant Profile

NPS loosestrife page

NPS Alien Plan Publications

Plant Profile