About four years ago, I found an unfamiliar plant in my yard. I watched it flower and liked the pretty red flowers. So I let it go to seed. Mistake.
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| hounds tongue, gypsyweed, Cynoglossum officinale |
Why was it a mistake? Because the next spring I had a dozen little plants. This time I read about it and discovered that it is houndstongue, Cynoglossum officinale, in the borage family, Boraginaceae. Not only is it an aggressive invader, the fine hairs on its stems and leaves give people contact dermatitis.
I pulled out the ones I could find. But, of course, an aggresive weed leaves dormant seeds in the soil. The battle is not over.
I have called this plant houndstongue, but some websites and reference books call it gypsyweed. When you search online for gypsyweed, the plant that comes up is Veronica officinalis (plantain family, Plantaginaceae, a very different plant). Then there are Cannabis strains called gypsy weed. Searching for houndstongue yields lots of relevant information. So gypsyweed seems to be a little-used common name. Houndstongue is also spelled hound's tongue and hound's-tongue. It is native to Europe. There are species of Cynoglossum native to North America, but Cynoglossum officinale is not.
Cynoglossum combines cynos, "of a dog," in Greek, and glossa "tongue." The species epithet officinale means "of the office", the herbalist's office, so, the medicinal plant. Europeans long used it medicinally. The leaf does resemble a dog's tongue.
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| houndstongue leaves |
I thought that it was a relatively new weed along the Colorado Front Range and maps in the Flora of Colorado show it mainly in the western half of the state. However, midwestern weed books from 20 years ago reported it, as a minor but toxic-to-livestock weed in many places across the Midwest, so presumably it has been here a while and is just reached my yard.
And the real problem with houndstongue is its toxicity. It contains pyrrolizidine alkaloids that kill liver cells and so cause irreversible liver damage. It can be fatal to livestock. It is dangerou even if the animal has eaten just a small amount (6% of hay for horses). Animals rarely eat it fresh, but it is just as toxic when dry. Horses and cattle are more susceptible than sheep, but in all cases it should not be eaten.
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| houndstongue, Cynoglossum officinale big leaves at the bottom will flower next year |
Historically in Europe, this was a medicinal plant. The root was boiled to treat coughs and sore throats, and taken as pills for head colds and shortness of breath. The above-ground plant, boiled in wine, treated dysentery. The leaves in hog's lard formed a salve that was applied to keep hair from falling out or ease the pain of a burn. They laid a green leaf on a fresh wound to speed healing.
For centuries, European medicine was influenced by the Doctrine of Signatures. The Doctrine of Signatures explained that God marked plants with what they are to be used for. Houndtongue's leaves looked like a dog's tongue. Grieve quotes Gerard (1600s) writing that you could stand on a leaf of hound's tongue and dogs will not bark at you. References from Roman times and throughout the Middle Ages claimed that boiled or in an ointment, houndstongue protected from and cured bites from mad dogs, (Rabies from dog bites was a serious concern.)
I do not find the statement that standing on the leaf, the dog won't bark at you, which I found in Grieve, in the edition Gerard that I have. However, Gerard did write "The leaves stink very filthily, much like to the pille of dogs, wherefore the Dutchmen call it Hound's pille, and not Hound's tongue." (p. 803) and he mentioned the stink of the plant again in his description. I don't remember a stink; check this point if you see houndstongue.
Modern medical sources mainly consider houndstongue too toxic to be used as a medicine; certainly there are safer choices.
Houndstongue is a biennial; the first year you see only a cluster of leaves on the ground. The second year it grows into the tall flowering plant. Like others in the borage family, the growing flower heads develop in an attractive curve. The flowers are a rich deep red.
The seeds are small and covered in tiny barbed hairs so that they cling. For people raising sheep for wool, that is an added problem with houndstongue as a weed; the seeds are difficult to remove from a fleece and lower its value.
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| houndstongue, Cynoglossum officinale |
Green seed pods are developing on these branches
I have seen it growing in the Netherlands, in low spots near the coast. There it is a native wildflower. In Ireland, it has become quite rare, arousing concern. That is too common right now: a plant that is not doing well in places where it is native and at the same time is a hated weed elsewhere in the world.
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| houndstongue, Cynoglossum officinale in the Netherlands |
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| houndstongue, Cynoglossum officinale, Boulder Colorado |
Comments and corrections welcome.
References
Ackerfield, J. 2022. Flora of Colorado. 2nd edition. BRIT Press. Fort Worth, Texas.
Colorado State University. Guide to Poisonous Plants. Houndstongue. https://poisonousplants.cvmbs.colostate.edu/plant/37
Culpeper, N. 1880. Culpeper's Complete Herbal. Originally 1652. online:. link
Devlin, Z. 2021. The wildflowers of Ireland. 2nd. edition. Gill Books. Dublin, Ireland.
Fernald, M.L. 1970. Gray's Manual of Botany. 8th ed. D. Van Nostrand Company. New York. (meaning of Cyanoglossum)
Franklin County Noxious Weed Control Board. Houndstongue: Options for control. Washington State Noxious Weed Control Board https://www.nwcb.wa.gov/images/weeds/Houndstongue_Franklin.pdf
Gerard, J. 1975. Hound's-tongue The Herbal. originally 1633. Dover Reprint. Dover Publications. New York. online: link Chapt. 286.
Grieve, M. 1971. A Modern Herbal. Originally 1931. Dover Reprint. Dover Publications. New York. online: link
Invasive Plant Atlas. 2018. Houndstongue, Invasive Plant Atlas link
Northwest Invasive Plants Council. 2025. Hound's-tongue. Northwest Invasive Plants Council. link.
Stubbendieck, J., M.J. Coffin, and L. M. Landholt. 2003. Weeds of the Great Plains. Nebraska Department of Agriculture. Lincoln, Nebraska.
Kathy Keeler, A Wandering Botanist
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