Houndstongue
Cynoglossum officinale
Washington State Classification
Class B — Control Required (Designated)
Houndstongue is a very strong competitor of desirable forage and is poisonous.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
Houndstongue is a biennial or short-lived perennial that begins as a rosette the first year and then produces stems that grow 1 to 4 feet tall. It develops a taproot that is thick, woody, black and branching. All parts are covered with hairs.
Leaves
Leaves are hairy and rough. Lower leaves are 4 to 12 inches long, about 1 to 2 inches (sometimes 3) wide, and have petioles (leaf stalks). Some say these resemble a hound's tongue - where it gets its common name. Upper leaves are similar, but reduce in size up the stem, and are alternately arranged and without petioles (attach directly to the stem).
Flowers
Flower in clusters at the ends up upper stems. Flowers are a dull reddish-purple to burgundy, ~1/4 inch wide, and have 5 lobes.
Fruit & Seeds
Flowers form 4 nutlets, with each nutlet containing one seed. Nutlet surface is covered with barbed hooks that allow itself to be attached to animals and people for dispersal. These can also greatly reduce the value of wool.
Impact
Houndstongue is a very strong competitor of desirable forage and is poisonous. It contains pyrrolizidine alkaloids that stop the reproduction of liver cells and is toxic to cattle, horses, goats and other livestock. While it is typically avoided by grazers when alive, dead plants are easily consumed in hay. Plants can also cause dermatitis in humans.
Ecology & Spread
Habitat
Houndstongue is found on roadsides, meadows and in disturbed areas. It grows in open areas and is shade tolerant, found in woodlands and forest edges, and thrives in wetter grasslands. Please click here to see a county level distribution map of houndstongue in Washington.
Spread Mechanisms
Reproduction
Houndstongue reproduces by seed and is self pollinating. Seed production varies from ~300 to 2,000+ per plant. Seeds remaining on the soil surface can remain viable two to three years.
"
Control Methods
Mechanical
- Plants can be pulled and dug out, making sure to remove as much of the roots as you can. Rosettes can also be cut, making sure to sever below the root crown. Monitor for resprouts and seedlings, controlling plants prior to seed production. Flowering plants can be cut/mowed to the base and properly disposed of to greatly reduce and prevent seed production. Monitor and repeat as necessary. Repeat cultivation of young rosettes, in the autumn or early spring, provides effective control.
Biological Control
- Research is ongoing. There are currently no approved biological control agents available.