Woad
Isatis
- Known today as
- Isatis tinctoria. A biennial of the mustard family whose fermented leaves yielded Europe’s principal blue dye before indigo.
- Kind
- Plant, in 2 older authorities
- Constituents
- indican and isatan B, indigo and indirubin, glucobrassicin, 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.
Woad: what was it used for?
The dominant blue dye of medieval Europe, grown on an industrial scale in England, France, Germany, and Italy; the Languedoc around Toulouse grew rich on its trade.
Woad: what does modern science say?
A genuine historical textile dye; the war-paint legend does not survive scrutiny.
Pharmacognosy & Toxicology
- Constituents
- indican and isatan Bindigo precursors in the leaf
- indigo and indirubinthe dye
- glucobrassicin ChEMBLa glucosinolate
- tryptanthrin ChEMBL
- Mechanism
- The leaf’s indoxyl glycosides are fermented and oxidised to indigo, the blue; indirubin from the same chemistry is the active principle of the Chinese leukaemia remedy danggui longhui wan, a kinase inhibitor, and the root (ban lan gen) is the most used antiviral of the Chinese pharmacopoeia, with laboratory activity and weak trials. The plant is not psychoactive and the Britons’ war paint is Caesar’s one sentence.
- Checked against ChEMBL
- indirubin: Measured, as the entry says (“a kinase inhibitor”): Cyclin-dependent kinase 2 (human), IC50 3 nM, CHEMBL6134823; Glycogen synthase kinase-3 beta (human), IC50 4 nM, CHEMBL3745682.
- Toxic dose
- Safe.
- Standing
- A dye plant; Isatis root and leaf are in the Chinese Pharmacopoeia.
- Hoessel, R., et al. (1999). “Indirubin, the active constituent of a Chinese antileukaemia medicine, inhibits cyclin-dependent kinases.” Nature Cell Biology 1. Verified against its record · doi:10.1038/9035
- Speranza, J., et al. (2020). “Isatis tinctoria L. (woad): a review of its botany, ethnobotanical uses, phytochemistry, biological activities, and biotechnological studies.” Plants 9. Verified against its record · doi:10.3390/plants9030298
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.
Woad: what lore surrounds it?
The popular claim that the ancient Britons and Picts painted themselves blue with woad for battle rests on Julius Caesar’s report that the Britons dyed themselves with vitrum, a word that more often means “glass” than “woad,” and the woad reading may owe more to the interests of early modern woad growers than to Caesar. Lindow Man, the preserved Iron Age body sometimes cited as evidence, in fact bore a copper- or iron-based pigment, and modern experiments have found woad too caustic to tattoo. Its real history is commercial rather than martial: it lost its dominance only when indigo arrived from the New World in the sixteenth century.
Woad: what did the older authorities say?
- Pliny
- Woad enters the Natural History as body paint. “There is a plant in Gaul, similar to the plantago in appearance, and known there by the name of ‘glastum:’ with it both matrons and girls among the people of Britain are in the habit of staining the body all over, when taking part in the performance of certain sacred rites; rivalling hereby the swarthy hue of the Æthiopians, they go in a state of nature.”
- Culpeper
- A cold and dry plant of Saturn; some affirm it destructive to bees; “the herb is so drying and binding, that it is not fit to be given inwardly”; an ointment of it stanches bleeding, a plaster over the spleen takes away its hardness, and it quenches St Anthony’s fire.
Sources
- Wikipedia, “Isatis tinctoria.” Book, not indexed
- Pliny the Elder, Natural History 22.2, trans. J. Bostock & H. T. Riley (1855), Perseus Digital Library. Primary text
- Culpeper, N. (1653). The Complete Herbal, “Woad.” 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
- The mechanism read against ChEMBL (ChEMBL 37): curated mechanisms and measured activity
- Each quotation from the older authorities checked word for word against the text, read in full
- Sources
- 5 cited: 2 verified against its record, 2 primary text, 1 book, not indexed. 2 with the abstract on file.
- 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
“Woad.” 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/woad.
- MLA
“Woad.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 1 Oct. 2026, thethinkingpress.org/materia-medica/woad. Accessed 8 Oct. 2026.
- APA
Woad. (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/woad
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See Also
Also in Pliny the Elder
Wood sorrel in Pliny the Elder · Wild rue in Pliny the Elder · Woodlouse in Pliny the Elder · Wild garlic in Pliny the Elder · everything Pliny the Elder names →
Also in Nicholas Culpeper
Valerian in Nicholas Culpeper · Woody nightshade in Nicholas Culpeper · Tormentil in Nicholas Culpeper · everything Nicholas Culpeper names →
Drawing on the same sources: Wikipedia, Culpeper
Nearby in the alphabet
Witches’ butter (Black or yellow jelly fungi that swell on dead branches after rain) · Witch marks (Symbols scratched or burned near doors and fireplaces) · Witch bottle · Wormwood, oil of (Artemisia absinthium) · Witch ball (often silvered or colored, hung in the window)
Historical description, not medical advice.