Purple loosestrife

Purple loosestrife

Key identifying traits

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  Has long, showy, rose-purple flower spikes
  
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  Flowers are small, numerous & have 5-7 petals
  
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  Usually associated with moist or marshy areas
  
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  Leaves simple, entire, and opposite or whorled
  
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  Forms substantial root wads with many stems
  
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  Has erect stems, often growing 6 to 10 feet tall
  
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  Stems are stiff and four-sided
  
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  Develops root rhizomes and abundant seeds
  
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  Both a woody tap root and fibrous root system
  

Biology and ecology

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  An attractive rhizomatous perennial; reproduces by seed, roots and vegetative growth
  
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  Forms up to 2.5 million, pepper-size seeds per plant; seeds float on water and stick to animals
  
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  Commonly displaces desirable wildlife habitat
  
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  Only bees make good use of infested habitat
  
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  Dense infestations can impede water flow
  
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  Infestations often arise from ornamental use
  
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  Sometimes confused with fireweed and spiraea
  

Control

Chemical – Non-selective or broad leaf herbicides can be effectively used depending on site; if plants are in bloom, clip/bag flowers prior to spray; special care, permit and license required for aquatic applications