# Mustard seed (Brassica napus)

**Seme di napo*, 1660*

**Known today as.** The English follows the 1674 text as “mustard”; the 1660 printing, whose Italian is given in the heading, reads sem. napi, the seed of rape (*Brassica napus*), a close relative.

Kind: Plant

## What did Canale use it for?

Powdered, with squill oxymel and radish, as a vomit (ch. 5).

## What does modern science say?

Mustard in warm water is a genuine emetic and was long used in first aid for poisoning, a practice poison centers now advise against.

## Pharmacognosy and toxicology

- **sinigrin**: a glucosinolate
- **allyl isothiocyanate**: the pungent oil, freed by the seed’s own enzyme

**Mechanism.** Allyl isothiocyanate activates TRPA1 and inflames the skin: the mustard plaster.

**Dose.** Blisters from a plaster left too long; the oil is a lachrymator.

**Standing.** A food.

## What lore surrounds it?

Folkard notes that “Small as a grain of Mustard-seed” was a common Jewish comparison and that the mustard-tree of the parable “is not, however, the English Mustard (Sinapis nigra), but a tree called by the Arabs Khardal (Salvadora Persica).” In India “by means of the seed the Hindus discover witches”: lamps are lit at night, mustard-seed oil is dropped on water “pronouncing the while the name of every woman in the village,” and a female shadow in the water “is a sure sign that such woman is a witch.” The seed “symbolises generation” in the Hindu tale of the Rose of Bakawali, where a childless wife tastes the pressed oil and conceives.

Thiselton-Dyer adds the Gloucestershire phrase for a sad and severe countenance, “He looks as if he lived on Tewkesbury mustard,” the town “having been long noted for its ‘mustard-balls made there, and sent to other parts,’” and Falstaff's “wit as thick as Tewkesbury mustard.”

Grieve: the Greek physicians “attributed its discovery to Æsculapius”; the name comes “from mustum (the must), or newly-fermented grape juice, and ardens (burning),” the Romans having pounded the seed in new wine. Coles in 1657 says “about Teuxbury they grind Mustard seed and make it up into balls which are brought to London and other remote places as being the best that the world affords,” and all mustard was sold in balls “till Mrs. Clements, of Durham, at the close of the eighteenth century, invented the method of preparing mustard flour.”

## What did the older authorities say?

**Matthew 13:31.** The kingdom of heaven is like a grain of mustard seed, the least of all seeds, that becomes a tree.

## Sources

- Folkard, R. (1884). *Plant Lore, Legends, and Lyrics*, “Mustard.” Project Gutenberg #44638.
- Thiselton-Dyer, T. F. (1889). *The Folk-lore of Plants*. Project Gutenberg #10118.
- Grieve, M. (1931). *A Modern Herbal*, “Mustards.” botanical.com/botanical/mgmh/m/mustar65.html
- Grieve, M. (1931). *A Modern Herbal*.

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*Mustard seed.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-01. The Thinking Press. https://thethinkingpress.org/materia-medica/mustard-seed

Historical description, not medical advice.