Blackthorn
Sloe
- Known today as
- Prunus spinosa. A thorny hedgerow shrub bearing small, bitter, blue-black plums, sloes, after the first frost.
- Kind
- Plant, in 1 older authority
- Constituents
- amygdalin, proanthocyanidins, quercetin and kaempferol glycosides
- Poisoning
- Cyanide from the kernels
- Earliest authority here
- Culpeper (1616–1654)
- 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.
Blackthorn: what was it used for?
Sloes made into wine, syrup, and sloe gin; the bark and flowers used as an astringent and a mild laxative in the older herbals.
Blackthorn: what does modern science say?
The fruit is a genuine source of tannins and vitamin C once cooked or frosted; raw sloes are too astringent to eat.
Pharmacognosy & Toxicology
- Constituents
- amygdalin ChEMBLin the kernel; a cyanogenic glycoside
- proanthocyanidinsin the fruit and bark
- quercetin and kaempferol glycosidesin the flower
- Mechanism
- The flower is a mild laxative and diuretic by its flavonoids; the fruit is astringent by its tannins; the kernels, like all Prunus kernels, release cyanide when crushed and eaten.
- Toxic dose
- The fruit and flower are safe; kernels in quantity are not, and a handful of bitter kernels has poisoned children in the related species.
- Syndrome
- Cyanide from the kernels
- Standing
- The flower is in the German tradition (Commission E, 1990) for mild constipation; no clinical trials.
- Blumenthal, M., ed. (1998). The Complete German Commission E Monographs, “Blackthorn flower.” Standard reference work
- Bolarinwa, I. F., et al. (2014). “Amygdalin content of seeds, kernels and food products commercially available in the UK.” Food Chemistry 152. Verified against its record · doi:10.1016/j.foodchem.2013.11.002
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.
Blackthorn: what lore surrounds it?
Blackthorn was called the witches’ own tree in the British Isles, its wood cut for wands and staffs and its thickets said to shelter fairies; Thomas Weir of Edinburgh, the “Wizard of West Bow,” was said to carry a blackthorn staff carved with a satyr’s head, given him by the Devil. Irish tradition made its timber into the shillelagh, and English country sayings call a sudden cold snap during its early blossom a “blackthorn winter,” while “many sloes, many groans” and “many sloes, many cold toes” read a heavy crop as the omen of a hard winter.
Blackthorn: what did the older authorities say?
- Culpeper
- “It is so well known, that it needs no description.” The fruit “ripens after all other plums whatsoever, and is not fit to be eaten until the Autumn frost mellow them.” “All the parts of the Sloe-Bush are binding, cooling, and dry, and all effectual to stay bleeding at the nose and mouth, or any other place; the lask of the belly or stomach, or the bloody flux.” The distilled water of the flowers, “first steeped in sack for a night,” is “a most certain remedy, tried and approved, to ease all manner of gnawings in the stomach, the sides and bowels,” and the leaves make lotions “to gargle and wash the mouth and throat.”
Sources
- Royal Botanic Garden Edinburgh, “The Blackthorn Tree of British and Irish Folklore.” Book, not indexed
- Culpeper, N. (1653). The Complete Herbal, “The Black Thorn, Or Sloe-Bush.” 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: 1 verified against its record, 1 primary text, 1 standard reference work, 1 book, not indexed. 1 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
“Blackthorn.” 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/blackthorn.
- MLA
“Blackthorn.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 1 Oct. 2026, thethinkingpress.org/materia-medica/blackthorn. Accessed 8 Oct. 2026.
- APA
Blackthorn. (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/blackthorn
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See Also
Poisoned alike: cyanide from the kernels
Sharing amygdalin, proanthocyanidins, quercetin and kaempferol glycosides
Also in Nicholas Culpeper
Broom in Nicholas Culpeper · Bistort in Nicholas Culpeper · Burdock in Nicholas Culpeper · Asarabacca in Nicholas Culpeper · everything Nicholas Culpeper names →
Drawing on the same sources: Culpeper, Blumenthal
Nearby in the alphabet
Bladderwrack (a brown seaweed of rocky shores, buoyed by paired air bladders) · Black walnut · Blessed ashes (blessed on Ash Wednesday) · Black pepper (The dried fruit of Piper nigrum) · Blessed bread (distinct from the Eucharist) · Black hellebore (Helleborus niger) · Blessed candles (and the Paschal candle) · Bitter aloes (A)
Historical description, not medical advice.