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houndstongue (Cynoglossum officinale)
ODA rating: B
Oregon houndstongue distribution
Other common names
Hounds tongue, gypsy flower, rats and mice, dog bur
Click on photo to view larger image
Photo by Rich Old, XID Services
Photo by Rich Old, XID Services

Photo by Tom Forney, Oregon Department of Agriculture
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Biennial; blooms June to August. Grows 1 to 4 ft tall; forms rosette first year and sends up flowering stalk second year. Leaves alternate, rough, hairy (resembling a hound’s tongue) and 1 to 12 inches long. Flowers reddish purple and terminal. Seeds nutlets.
Houndstongue can be a serious problem in rangeland and pasture. The weed is highly invasive and can significantly reduce forage. The plant produces barbed seeds, or burrs, which allow the plant to readily adhere to hair, wool, and fur and can in turn reduce the value of sheep wool.  In addition houndstongue contains large quantities of pyrrolizidine alkaloids which are toxic to cattle and horses.
Known hazards
Houndstongue is toxic, containing pyrrolizidine alkaloids, causing liver cells to stop reproducing. Animals may survive six months or longer after they have consumed a lethal amount. Sheep are more resistant than cattle or horses.
This plant was introduced to North America as a contaminant of cereal seed in the late 1800s
Distribution in Oregon

Biological controls
No approved biological control agent is currently available. However, research is being conducted on five promising insects: a root weevil, a stem weevil, a seed weevil, a root beetle and a root fly.