Weed of the Week

5-12-08

Hairy Willow Herb, Epilobium hirsutum

                          

Photo credits: Jeff Delonge for Wikopedia.com

 Characteristics:

Family: Onagraceae (Evening Primrose Family)

Origin: Native to Eurasia

Description:

• Perennial

• Found in moist environments

Stems:

• 3-6 feet in height

• Covered in soft hairs

Flowers:

• Showy pink flowers 3/4 " in width

• Four notched petals

• 8 stamens

Leaves:

• Leaf arrangement mostly opposite

• Lanceolate shaped leaves (longer than wide)

• Leaf margins finely toothed

Fruit:

• Oblong and flattened with a tuft of long white hairs

• Occurs at the top of the stem

• Flowering from July through August

Additional information:

Hairy Willow Herb also spreads by rhizomes (roots) and can self pollinate.  Hairy Willow Herb is listed on the Colorado State Noxious Weed Watch List.  It has been found twice in the State most recently in Broomfield County in the Wildgrass Open Space Area.  The County is currently taking control measures and has contacted the State Department of Agriculture.

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