# Adder’s-tongue fern (Ophioglossum vulgatum)

*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

## 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.

## What does modern science say?

No controlled evidence supports its wound or internal uses.

## Pharmacognosy and toxicology

- **ophioglossin**: a flavonoid glycoside
- **quercetin**: 
- **3-O-methylquercetin**: 

**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.

**Dose.** No toxicity recorded at the doses of folk use.

**Standing.** No monograph, no clinical trial; a plant of folk use only.

## 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.

## 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*.”
- Culpeper, N. (1653). *The Complete Herbal*, “Adder’s Tongue Or Serpent’s Tongue.” Project Gutenberg #49513.
- Clericuzio, M., et al. (2012). “Flavonoid oligoglycosides from *Ophioglossum vulgatum*.” *Planta Medica* 78.
- Allen, D. E., and Hatfield, G. (2004). *Medicinal Plants in Folk Tradition*. Timber Press.

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*Adder’s-tongue fern.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-01. The Thinking Press. https://thethinkingpress.org/materia-medica/adders-tongue-fern

Historical description, not medical advice.