Oak galls
Oak apples; gallae
- Known today as
- Round growths raised on oaks by gall wasps.
- Kind
- Plant, in 1 older authority
- Constituents
- tannic acid, gallic acid
- Earliest authority here
- Pliny (AD 23/24–79)
Revised October 1, 2026: An older authority added from a text read in full. Version 1, first published September 25, 2026.
Oak galls: what was it used for?
The strongest of astringents, for fluxes, bleeding, and sore gums; and, with iron, the ink of the West.
Oak galls: what does modern science say?
Rich in tannic acid, genuinely astringent.
Pharmacognosy & Toxicology
- Constituents
- tannic acid ChEMBLup to 70 per cent of the Aleppo gall
- gallic acid ChEMBL
- Mechanism
- Tannic acid precipitates proteins: it tans leather, inks paper with iron, and tightens tissue, which is the astringent use; given for burns in the 1920s it caused liver damage and was abandoned.
- Toxic dose
- Grams by mouth injure the liver; the burn treatment killed.
- Standing
- Tannic acid survives in a few preparations for cold sores and in the laboratory.
- Wells, D. B., Humphrey, H. D., and Coll, J. J. (1942). “The relation of tannic acid to the liver necrosis occurring in burns.” New England Journal of Medicine 226. Matched to its record and reviewed
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.
Oak galls: what lore surrounds it?
Iron-gall ink, made from galls and vitriol, wrote most of the manuscripts of the Middle Ages.
English folk custom read the coming year in them: an oak apple opened on Michaelmas Day that held a worm foretold a pleasant, ordinary year; a spider, shortage and ruined crops; a fly, a moderate season; and nothing at all, the worst sign, serious disease throughout the year.
Oak galls: what did the older authorities say?
- Pliny
- “All the glandiferous trees produce the gall-nut as well.” The gall-nut of the hemeris oak “is considered the choicest of all, and the best adapted for the preparation of leather,” while the black gall-nut is “deemed preferable for dyeing wool.” Pliny says the gall-nut begins to grow “just as the sun is leaving the sign of Gemini, and always bursts forth in its entirety in a single night”; the white kind grows in a single day and reaches about the size of a bean, the black sometimes “the size of an apple even.” The best come from Commagene, the worst from the robur, and a gall “may easily be tested by means of certain holes in it which admit of the passage of the light.”
Sources
- Pliny, Natural History XVI. Primary text
- Dioscorides, De materia medica. Read in part · the text read
- Wikipedia, “Oak apple.” Book, not indexed
- Pliny the Elder, Natural History 16.9, trans. J. Bostock & H. T. Riley (1855), Perseus Digital Library. 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
- 5 cited: 1 read in part, 1 matched to its record and reviewed, 2 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 25, 2026 · last revised October 1, 2026
- Chicago
“Oak galls.” 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/oak-galls.
- MLA
“Oak galls.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 1 Oct. 2026, thethinkingpress.org/materia-medica/oak-galls. Accessed 8 Oct. 2026.
- APA
Oak galls. (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/oak-galls
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See Also
Sharing gallic acid
Also in Pliny the Elder
Olive oil and holy water in Pliny the Elder · Nutmeg and clove in Pliny the Elder · Orache in Pliny the Elder · Niter, pills of in Pliny the Elder · everything Pliny the Elder names →
Drawing on the same sources: Pliny, Dioscorides, Wikipedia
Orpiment and realgar · Opium poppy · Mullein · Opopanax · Pearls, prepared · the bibliography →
Nearby in the alphabet
Oil of bricks · Oil of catechumens · Oil of the sick · Nettle seed (Urtica dioica) · Nepenthe (Unidentified)
Historical description, not medical advice.