# Hazel (Corylus avellana)

**Corylus**

**Known today as.** *Corylus avellana*.

Kind: Plant

## What was it used for?

The nuts as food; the catkins for coughs.

## What does modern science say?

A nutritious nut; no other medicinal effect.

## Pharmacognosy and toxicology

- **oleic acid**: the nut oil
- **Cor a 1**: the pollen-related allergen of the nut
- **taxifolin**: in the leaf
- **tannins**: in the bark and catkin

**Mechanism.** The nut is a food rich in monounsaturated fat and vitamin E; the catkins and bark are astringent. Hazelnut allergy, cross-reacting with birch pollen, is among the commonest tree-nut allergies of Europe.

**Dose.** A food; anaphylaxis in the allergic.

**Standing.** A food; the leaf has a listing in French traditional use for venous complaints.

## What lore surrounds it?

The wood of wisdom in Irish tradition, and of the dowser’s rod, used to find water, metal, and hidden things.

Irish tradition held that hazels of wisdom grew over the sacred wells at the sources of Ireland’s chief rivers, dropping their nuts into the water; the salmon that ate them gained wisdom by the number eaten, which is why the salmon of wisdom gave Fionn mac Cumhaill all knowledge. Hazel was so sacred to the poets that burning it as common fuel was taboo, and its wood was the favored choice for both witches’ wands and dowsers’ rods.

## What did the older authorities say?

**Georgius Agricola.** Pictures miners seeking veins of ore with a forked hazel twig, the divining rod, though he doubted it.

## Sources

- Agricola, G. (1556). *De re metallica*.
- Druidry.org, “Hazel.”
- Wikipedia, “Celtic sacred trees.”
- Flinterman, A. E., et al. (2008). “Hazelnut allergy: from pollen-associated mild allergy to severe anaphylactic reactions.” *Current Opinion in Allergy and Clinical Immunology* 8.

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*Hazel.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-09-25. The Thinking Press. https://thethinkingpress.org/materia-medica/hazel

Historical description, not medical advice.