Wood sorrel
Oxalis; Irish seamsóg
- Known today as
- Oxalis acetosella. A delicate woodland plant with clover-like, sour-tasting leaves of three leaflets and white, veined flowers.
- Kind
- Plant, in 2 older authorities
- Constituents
- oxalic acid and potassium oxalate, vitamin C, flavonoids
- Poisoning
- Oxalate poisoning
- 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.
Caution. Contains oxalic acid; avoid in quantity, especially with a history of kidney stones.
Wood sorrel: what was it used for?
The leaves eaten fresh or made into a cooling drink for their sharp, lemony taste, and used as a folk remedy for fevers and scurvy.
Wood sorrel: what does modern science say?
Its sharp taste comes from oxalic acid, mildly toxic in quantity and best avoided by those prone to kidney stones.
Pharmacognosy & Toxicology
- Constituents
- oxalic acid and potassium oxalatethe sour, up to 1 per cent fresh
- vitamin C ChEMBL
- flavonoids
- Mechanism
- The lemon taste is oxalate, which cools in the Galenic sense and binds calcium in the kidney in quantity; the vitamin C was the scurvy use. Salt of sorrel (potassium hydrogen oxalate), once extracted from it, was the stain remover and a poison of the nineteenth century.
- Toxic dose
- A few leaves are safe; sheep and children eating it in quantity have had oxalate poisoning.
- Syndrome
- Oxalate poisoning
- Standing
- A wild food; no monograph.
- Frohne, D., and Pfänder, H. J. (2005). Poisonous Plants, 2nd ed., “Oxalidaceae.” Book, not indexed
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.
Wood sorrel: what lore surrounds it?
Wood sorrel is one of the leading candidates, with young clover, for the true shamrock with which St. Patrick is said to have explained the Trinity, a legend first recorded only in 1726, more than a thousand years after his lifetime, and absent from earlier English accounts of the Irish shamrock custom. The confusion may go back to English writers mishearing the Irish seamsóg, wood sorrel, as seamróg, young clover. Surveys of what the Irish actually call shamrock have never settled the question, with lesser and white clover far outnumbering wood sorrel among modern answers.
Wood sorrel: what did the older authorities say?
- Pliny
- Pliny's whole account of the oxys fits in a sentence: “The oxys is a plant with three leaves; it is given for derangement of the stomach, and patients eat it who are suffering from intestinal hernia.”
- Culpeper
- Venus owns it; it serves all the purposes of the other sorrels and is more effectual against putrefaction of the blood and ulcers of the mouth, to quench thirst and stay vomiting; its juice turns red when clarified “and makes a most dainty clear syrup”; gargled, it helps “a foul stinking canker.”
Sources
- Wikipedia, “Shamrock.” Book, not indexed
- Pliny the Elder, Natural History 27.89, trans. J. Bostock & H. T. Riley (1855), Perseus Digital Library. Primary text
- Culpeper, N. (1653). The Complete Herbal, “Wood Sorrel.” 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
- Each quotation from the older authorities checked word for word against the text, read in full
- Sources
- 4 cited: 2 primary text, 2 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 27, 2026 · last revised October 1, 2026
- Chicago
“Wood sorrel.” 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/wood-sorrel.
- MLA
“Wood sorrel.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 1 Oct. 2026, thethinkingpress.org/materia-medica/wood-sorrel. Accessed 8 Oct. 2026.
- APA
Wood sorrel. (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/wood-sorrel
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See Also
Poisoned alike: oxalate poisoning
Chaga · Sorrel, syrup of · Purslane · the syndrome, with all of them →
Sharing vitamin C, flavonoids
Lepidium sativum · Sorbus aucuparia · Rosa gallica · Euphrasia officinalis · Capsella bursa-pastoris · Hepatica nobilis · Buphthalmum salicifolium
Also in Pliny the Elder
Woodlouse in Pliny the Elder · Woad in Pliny the Elder · Yarrow in Pliny the Elder · Wild rue in Pliny the Elder · everything Pliny the Elder names →
Also in Nicholas Culpeper
Woody nightshade in Nicholas Culpeper · Yellow dock in Nicholas Culpeper · Valerian in Nicholas Culpeper · everything Nicholas Culpeper names →
Drawing on the same sources: Wikipedia, Culpeper, Frohne
Yew · Gorse · Herb Paris · the bibliography →
Nearby in the alphabet
Witches’ butter (Black or yellow jelly fungi that swell on dead branches after rain) · Wormwood, oil of (Artemisia absinthium) · Witch marks (Symbols scratched or burned near doors and fireplaces) · Witch bottle
Historical description, not medical advice.