Houndstongue
Cynoglossum, “dog’s tongue”
- Known today as
- Cynoglossum officinale. A coarse, grey-leaved biennial of waste ground, named for its long, tongue-shaped, softly hairy leaves.
- Kind
- Plant, in 1 older authority
- Constituents
- heliosupine, echinatine, allantoin, and 1 more
- Earliest authority here
- Pliny (AD 23/24–79)
- In other databases
- Plants of the World Online search · GBIF search · Wikidata search
Revised October 1, 2026: An older authority added from a text read in full. Version 1, first published September 27, 2026.
Caution. Toxic to the liver.
Houndstongue: what was it used for?
Applied as a poultice for wounds, burns, and dog bites, and taken for coughs, in the older European herbals.
Houndstongue: what does modern science say?
The plant contains pyrrolizidine alkaloids that damage the liver, and it has no place in modern medicine.
Houndstongue: is it poisonous?
Yes, in some form or dose. Toxic to the liver. Its poisoning is pyrrolizidine alkaloids (veno-occlusive disease): Weeks to months of use. Historical description, not medical advice; in a poisoning, call a poison centre.
Pharmacognosy & Toxicology
- Constituents
- heliosupine ChEMBLa pyrrolizidine alkaloid, up to 1.5 per cent
- echinatine ChEMBL
- allantoin ChEMBL
- tannins
- Mechanism
- Externally the allantoin and tannins soothe and tighten; internally the pyrrolizidine alkaloids are among the most concentrated in any European herb and are converted in the liver to pyrroles that block the hepatic veins and alkylate DNA. It kills horses and cattle that eat it in hay.
- Toxic dose
- No safe internal dose; the alkaloid load is above comfrey’s.
- Syndrome
- Pyrrolizidine alkaloids (veno-occlusive disease)
- Standing
- Internal use is warned against across Europe, where regulators restrict pyrrolizidine alkaloids in herbal products; the plant is a noxious weed in the American West.
- Roeder, E. (1995). “Medicinal plants in Europe containing pyrrolizidine alkaloids.” Pharmazie 50. Verified against its record · doi:10.1002/chin.199528310
- Stegelmeier, B. L., et al. (1999). “Pyrrolizidine alkaloid plants, metabolism and toxicity.” Journal of Natural Toxins 8. Verified against its record · PMID 10091131
The abstract of each source, beneath its citation. For Club members. About the Club or sign in.
Constituent names open the compound’s record at PubChem, and “ChEMBL” beside a name opens its record at ChEMBL, the European Bioinformatics Institute’s database of bioactive molecules. Where a mechanism line was checked against ChEMBL (ChEMBL 37, read 1 October 2026), the check is shown with the measured value and its source paper, or says plainly that nothing has been measured. Doses are as the references give them, for description only; this is not medical advice. Each source carries the result of its check against Crossref, PubMed, or the authority’s page: see Verification.
Houndstongue: what lore surrounds it?
A textbook case of the doctrine of signatures: Giambattista della Porta pictured its leaves beside a dog’s head to argue that the likeness itself showed the plant’s power over the harm of dogs, the principle he stated as “that to which a sign belongs, to it also the effect belongs.”
Houndstongue: what did the older authorities say?
- Pliny
- The cynoglossos is the plant “the leaf of which resembles a dog's tongue, and which produces so pleasing an effect in ornamental gardening.” Pliny reports a fever cure keyed to the plant's form: “The root, it is said, of the kind which bears three stems surmounted with seed, is very useful, taken in water, for tertian, and of that with four stems, for quartan, fevers.” A similar plant bearing small burrs has a root, taken in water, “curative of wounds inflicted by frogs or serpents.”
Sources
- Wellcome Collection, doctrine of signatures illustration (della Porta, Phytognomonica). Book, not indexed
- Pliny the Elder, Natural History 25.41, trans. J. Bostock & H. T. Riley (1855), Perseus Digital Library. Primary text
Verification
- Checked
- October 1, 2026
- Passes
- Every sentence read against its sources, in the pass over the remaining 343 entries
- The Standing line checked against the authority it names (EMA, WHO, FDA, CITES, Commission E)
- Every dated or regulatory claim checked by category across the database
- Each quotation from the older authorities checked word for word against the text, read in full
- Sources
- 4 cited: 2 verified against its record, 1 primary text, 1 book, not indexed. 1 with the abstract on file.
- Corrections
- "prohibited across Europe" softened to warned against, with the EU restriction of pyrrolizidine alkaloids named.
What was checked, how, and what was found is set out on the Verification page. A checked source is one whose record was found; it does not make the entry medical advice.
Cite This Entry
Version 1 · first published September 27, 2026 · last revised October 1, 2026
- Chicago
“Houndstongue.” In Materia Medica, edited by B. C. P. Statema. Version 1. The Thinking Press, 2026–. Last modified October 1, 2026. https://thethinkingpress.org/materia-medica/houndstongue.
- MLA
“Houndstongue.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 1 Oct. 2026, thethinkingpress.org/materia-medica/houndstongue. Accessed 8 Oct. 2026.
- APA
Houndstongue. (2026, October 1). In B. C. P. Statema (Ed.), Materia medica (Version 1). The Thinking Press. Retrieved October 8, 2026, from https://thethinkingpress.org/materia-medica/houndstongue
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See Also
Poisoned alike: pyrrolizidine alkaloids (veno-occlusive disease)
Ragwort · Comfrey · Alkanet · Coltsfoot · Borage · Butterbur · the syndrome, with all of them →
Sharing allantoin, tannins
Pulmonaria officinalis · Snail · Sempervivum tectorum · Geum urbanum · Hepatica nobilis · Corylus avellana
Also in Pliny the Elder
Jet, oil of in Pliny the Elder · Honeyed wine and honeyed water in Pliny the Elder · Juniper in Pliny the Elder · Hawthorn in Pliny the Elder · everything Pliny the Elder names →
Drawing on the same sources: Wellcome Collection, Roeder, Stegelmeier
Nearby in the alphabet
Horehound (Marrubium vulgare) · Human fat (Fat rendered from the bodies of the executed) · Hop (Humulus lupulus) · Hungary water (steeped in spirit of wine and distilled) · Hyssop (Hyssopus officinalis) · Honey fungus (from black cords, the “shoestrings,” that spread beneath the bark)
Historical description, not medical advice.