Adder’s-tongue fern
Green Oil of Charity (the ointment made from it)
- Known today as
- Ophioglossum vulgatum. A small, unfern-like fern of old pastures, its single spike rising from a single blade said to resemble a serpent’s tongue.
- Kind
- Plant, in 1 older authority
- Constituents
- ophioglossin, quercetin, 3-O-methylquercetin
- Earliest authority here
- Culpeper (1616–1654)
- 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.
Adder’s-tongue fern: what was it used for?
Steeped in oil to make the “Green Oil of Charity,” a wound ointment of English folk medicine; a tea of the leaf was taken for internal bleeding and vomiting.
Adder’s-tongue fern: what does modern science say?
No controlled evidence supports its wound or internal uses.
Pharmacognosy & Toxicology
- Constituents
- ophioglossina flavonoid glycoside
- quercetin ChEMBL
- 3-O-methylquercetin ChEMBL
- Mechanism
- Flavonoids with weak anti-inflammatory and antioxidant action in vitro; nothing in the plant explains a wound action beyond the oil it was steeped in.
- Toxic dose
- No toxicity recorded at the doses of folk use.
- Standing
- No monograph, no clinical trial; a plant of folk use only.
- Clericuzio, M., et al. (2012). “Flavonoid oligoglycosides from Ophioglossum vulgatum.” Planta Medica 78. Verified against its record · doi:10.1055/s-0032-1315149
- Allen, D. E., and Hatfield, G. (2004). Medicinal Plants in Folk Tradition. Timber Press. Verified against its record · doi:10.1600/0363644042451053
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.
Adder’s-tongue fern: what lore surrounds it?
The name is the doctrine of signatures at work: a plant that looked like a snake’s tongue was read as a remedy for a snake’s harm, though no surviving source spells out a snakebite cure tied to the name.
Adder’s-tongue fern: what did the older authorities say?
- Culpeper
- “This herb has but one leaf,” from which rises a slender stalk “dented with small dents of a yellowish green colour, like the tongue of an adder serpent (only this is as useful as they are formidable).” It is “an herb under the dominion of the Moon and Cancer,” temperate in heat but dry in the second degree. The juice of the leaves drunk with distilled water of horsetail is “a singular remedy for all manner of wounds in the breast, bowels, or other parts of the body,” and the leaves boiled in oil of unripe olives and “set in the sun four certain days” make “an excellent green balsam, not only for green and fresh wounds, but also for old and inveterate ulcers.”
Sources
- Wikipedia, “Ophioglossum vulgatum.” Book, not indexed
- Culpeper, N. (1653). The Complete Herbal, “Adder’s Tongue Or Serpent’s Tongue.” Project Gutenberg #49513. 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.
- Corrections
- None were needed.
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
“Adder’s-tongue fern.” 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/adders-tongue-fern.
- MLA
“Adder’s-tongue fern.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 1 Oct. 2026, thethinkingpress.org/materia-medica/adders-tongue-fern. Accessed 8 Oct. 2026.
- APA
Adder’s-tongue fern. (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/adders-tongue-fern
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See Also
Sharing quercetin
Also in Nicholas Culpeper
Agrimony in Nicholas Culpeper · Yellow dock in Nicholas Culpeper · Alkanet in Nicholas Culpeper · Woody nightshade in Nicholas Culpeper · everything Nicholas Culpeper names →
Drawing on the same sources: Wikipedia, Culpeper
Nearby in the alphabet
Aflatoxin mould · Aconite (of the buttercup family) · Agarwood (oud) · Abracadabra (one letter shorter each time, into a narrowing triangle) · AGLA · Zedoary (of the ginger family, a bitter, camphor-scented root from India) · Agnus Dei (blessed by the pope (note LXX))
Historical description, not medical advice.