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Houndstongue (Cynoglossum officinale) is a biennial that grow 1 to 4 feet tall. Introduced from Europe, houndstongue is toxic and contains a pyrrolizidine alkaloid that causes liver cells to stop reproducing.  Most animals avoid eating it because of its foul odor.  Even if ingested as hay, it remains topic.  Animals may survive 6 months or longer after consuming a lethal amount.

Houndstongue inhabits pastures, meadows, roadsides and disturbed sites. During the first year of growth, houndstongue forms a rosette and a deep thick taproot. In the second year, a flowering stem is formed.  The flowers bloom, seeds are set and then the plant dies.

The name ‘houndstongue’ was coined because the rosette leaves are broad and oblong in shape resembling a dog’s tongue.  It can be up to 12” in length and 3” in width.  Leaves and stems are covered entirely in soft white hairs and leaves are soft to the touch.

The flowers of houndstongue are reddish-purple, have five petals and bloom from June to July.  Due to its Velcro-like seeds, houndstongue spreads easily and is highly invasive.  A single plant can produce up to 2,000 seeds.  If your clothes or pets become covered with these seeds, please pick them off and dispose of them in the garbage or a fire.  Throwing them on the ground will only start a new infestation.

Integrated Management of Houndstongue

  • Grubbing & Hand pulling: root crown must be removed
  • Chemical methods: Herbicides such as 2, 4-D, metsulfuron and chlorsulfuron have been used to manage houndstongue on range, wildland and pasture sites.

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  • Cutting, mowing & other forms of defoliation: Taproots often store nutrients to support normal flowering & seed production
  • Prescribed burnings: May destroy some seeds, but fire may stimulate germination and provide optimal growing conditions.
  • Biological control : not approved for release in US.

Source: MSU Extension MontGuide MT199709AG Revised 8/09

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