Cynoglossum officinale

Keys to Identification

  • A biennial that was introduced from Europe
  • Reproduces by seeds
  • Stem is erect, stout, heavy, 1-1/2 to 3 ft tall
  • Fowers are terminal and reddish-purple
  • Seeds about 1/3 in long, the outer surface covered with short barbed prickles
  • Contains alkaloids that may cause liver cells to stop reproducing

This information courtesy of the Colorado Natural Areas Program


Boraginaceae (Borage)

Other Names

Hound’s tongue, dog bur, gypsy flower



Legal Status

Colorado Noxious Weed List B



Biennial or short-lived perennial

Growth form



Flowers are reddish-purple, with five petals, arranged in panicles in the upper leaf axils.


The fruit is composed of four prickly nutlets each about 1/3 in long (Whitson et al. 1996)


Leaves are alternate, 1-12 in long, 1-3 in wide, rough, hairy, and lacking teeth or lobes (Whitson et al. 1996). Basal leaves are elliptical to oblanceolate and tapered at the base.


Houndstongue produces a single flowering stem. The stem is erect, stout, heavy, 1 1/2-3 ft tall and usually branched above.


Houndstongue has a thick, black, woody taproot.


Houndstongue forms a rosette the first year of its life cycle.

Similar Species


None known.


None known.



Houndstongue contains toxic alkaloids that stop liver cells from reproducing. Therefore, houndstongue reduces livestock and wildlife forage and grazing animals should be kept away from houndstongue infested areas. Animals may live six or more months after eating a lethal dose of houndstongue. Sheep are more resistant to houndstongue poisoning that cattle or horses. The burs may reduce the value of wool.


Houndstongue is an early sucessional species on recently disturbed sites.


Due to its toxicity to grazing animals, houndstongue should not be eaten by humans.

Habitat and Distribution

General requirements

Houndstongue prefers areas with more than 10% bare ground (Butterfield et al. 1996), and is common on gravelly, alkaline soils (Stubbendieck et al. 1995).


Houndstongue is found over much of North America. It grows on rangeland, pastures, abandoned cropland, roadsides, and waste places (Butterfield et al. 1996). Houndstongue is found on rangeland, pastures, and roadsides throughout Colorado up to about 9000 feet.


Houndstongue is a native of Eurasia that was introduced to North America as a contaminant in agricultural seed.


Life cycle

Houndstongue is a biennial that produces a rosette the first year. During the second year a flowering stem bolts and produces fruit.

Mode of reproduction


Seed production

Mature plants can produce up to 2,000 seeds (Butterfield et al. 1996).

Seed bank

Seeds remaining on the parent plant may remain viable for 2-3 years. Buried seed rarely survive more than one year (Butterfield et al. 1996).


Seeds stick to clothing and animals and have the ability to be spread great distances.


Butterfield, C., J. Stubbendieck, and J. Stumpf. 1996. Species abstracts of highly disruptive exotic plants. Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/othrdata/exoticab/exoticab.htm (Version 16JUL97).

Stubbendieck, J., G.Y. Friisoe and M.R. Bolick. 1995. Houndstongue. Weeds of Nebraska and the Great Plains. Nebraska Department of Agriculture, Bureau of Plant Industry, Lincoln, Nebraska. pg. 185.

Whitson, T.D.(ed.), L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D. Lee, R. Parker. 1996. Houndstongue. Weeds of the West. Western Society of Weed Science, in cooperation with the Western United States Land Grant Universities Cooperative Extension Services, Newark CA. pg. 202.

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