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Texas Invasive Species Institute

Texas Invasive Species Institute


Cynoglossum officinale

Class: Magnoliopsida
Order: Lamiales
Family: Boraginaceae
Duration and Habit: Biennial forb

Cynoglossum officinale

Photographer: Mary Ellen (Mel) Harte Source: Bugwood.org Copyright: CC BY-NC 3.0 US


Houndstongue is a short-lived forb that typically have 1-2 stems, but as many as 8 stems have been reported on one plant. In the first year the plant is in rosette form with hairy leaves that are up to one foot in length and 3 inches wide. Flowers can be purple to red and they produces four triangular, rounded seeds. The entire plant has soft white hairs on it.

Ecological Threat

Houndstongue is able to successfully establish in pastures and rangelands, severely threatening livestock (especially cattle and horses) with its toxicity. It carries an alkaloid poison that can kills livestock through the loss of liver cells. Thankfully, animals won’t normally graze on it, but if cured in hay, it is still toxic. Sheep are more resistant and horses are particularly susceptible.


In the first year of growth the plant is in a rosette form, and then produces a flowering stem in the second year. After the second year, the plant dies. Flowers bloom in June and July, and are pollinated by bees and butterflies. They then produce fruits that are called nutlets. Houndstongue only reproduces by seed, and each plant can produce anywhere from 50-2000 seeds in its lifetime. Despite the high numbers the nutlets are dispersed slowly, usually by attaching to animals, clothing and even vehicles. The root system of Houndstongue is made up of a deep taproot and extensive branching


Discovered in Oregon in 1893, and reached Montana in 1900. Now it is present in 40 states.

Native Origin


Current Location

U.S. Habitat: Establishes in disturbed areas especially, agricultural areas, grasslands/ranges, riparian zones, roadsides, and coastlands.

U.S. Present: AL, AR, AZ, CA, CO, CT, DC, DE, IA, ID, IL, IN, KS, KY, MA, MD, MI, MN, MO, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OR, PA, RI, SD, TN, UT, VA, WA, WV and WY.

For a state and county distribution map provided by EDD MapS click here


Resembles other Cynoglossum species, including Cynoglossum boreale, Cynoglossum grande, and Cynoglossum occidentale.


The best way to manage this toxic plant is prevention, which can be done by removing the plant before it flowers and removing seeds. Mechanical methods may not be practical in large stands on natural areas and rangelands. Control with herbicides is temporary, as it does not change those conditions that allow infestations to occur. Due to this, long term management requires an integrated approach of both mechanical and chemical means.


Fact Sheet: Hound's Tongue (Jan 2014; PDF | 700 KB)
Alberta Invasive Plants Council (Canada).

Boorman, L. A.; Fuller, R. M. 1984. The comparative ecology of two sand dune biennials: Lactuca virosa L. and Cynoglossum officinale L. The New Phytologist. 96(4): 609-629.

De Clerck-Floate, R.; Schwarzlander, M. 2002. Host specificity of Mogulones cruciger (Coleoptera: Curculionidae), a biocontrol agent for houndstongue (Cynoglossum officinale), with emphasis on testing of native North American Boraginaceae. Biocontrol Science and Technology. 12(3): 293-306.

Kedzie-Webb, S. and R.L. Sheley. 2009. Houndstongue: Identification, Biology and Integrated Management (PDF | 997 KB) Montana State University Extension. MontGuide MT199709AG.

Wilson, Linda M.; McCaffrey, Joseph P. 1999. Biological control of noxious rangeland weeds. In: Sheley, Roger L.; Petroff, Janet K., eds. Biology and management of noxious rangeland weeds. Corvallis, OR: Oregon State University Press: 97-115.

Internet Sources





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