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Aquatic and Wetland Vascular Plants of the Northern Great Plains

30. Lythraceae, the Loosestrife Family

2. Lythrum L. -- Loosestrife

2. Lythrum salicaria L. -- Purple loosestrife

Rarely glabrous to usually pubescent perennial 6-12 dm tall; stems often much-branched above with the ascending branches terminating in the showy, spikelike inflorescences. Leaves opposite to subopposite, rarely whorled, becoming alternate and bractlike in the inflorescence, linear-lanceolate to lanceolate, 3-10 cm long, 0.5-2 cm wide, acute at the tip, obtuse to cordate at the base. Flowers mostly 2-several in the axils of the bracts, trimorphic, the stamens and styles of 3 different lengths; calyx tube 4-6 mm long, sparsely to densely pubescent, with appendages 2-3X longer than the calyx lobes; petals 7-10 mm long; stamens usually 12. Jul--Aug. Intro. from Europe, often planted as an ornamental, occasionally escaping to wet ditches, stream banks and floodplains, especially e ND, e and c SD; (Naturalized over much of e and c U.S., s Can. and at a few locations in the w U.S.).

The introduction of purple loosestrife to North America has proven very detrimental to wetlands of the eastern U.S. and Canada. It is an exceedingly aggressive, though attractive, weed of marshes that successfully outcompetes native wetland species. The problem is most acute from central MN eastward to the Atlantic Coast. Unfortunately the plant is of little or no value to wildlife and appears to have no natural enemies here. Purple loosestrife has been widely used as an ornamental in our region, and prospects for the plant increasing in the northern plains are good.

GIF- Distribution Map

Map key

Previous Species -- Lythrum alatum Pursh
Return to Family -- Lythraceae - The Loosestrife Family
Next Species -- Rotala ramosior (L.) Koehne

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