Black Alder
Name of plant:
Black alder
Traditional Lore
Black alder (Alnus glutinosa) has long been associated with the wetlands, rivers, and lakeshores of Europe, where its remarkable water-resistant wood made it invaluable for bridges, piles, wells, and other structures exposed to moisture. In Celtic traditions, alder was regarded as a tree of importance and appears in the medieval Irish ogham alphabet as Fearn, often associated with protection, resilience, and the boundary between land and water. The bark, leaves, and cones were traditionally used for dyes and tanning, while folk medicine employed various parts of the tree for inflammatory conditions and minor ailments. Because freshly cut alder wood turns from pale white to a striking reddish-orange, the tree also inspired folklore linking it with blood, battle, and transformation, giving it a distinctive place in the imagination of many European cultures.
Family:
Betulaceae — Birch family
Genus and species:
*Alnus glutinosa* (L.) Gaertn.
Other names:
Black alder, European alder, Common alder, Alder, European black alder, Owler, Aller, Aune
Brief introduction:
Black alder is a deciduous tree native to Europe, northern Africa, western Asia, and parts of the Caucasus. It is particularly characteristic of wet ground, river margins, marshes, floodplains, and damp woodland. The tree is readily recognized by its rounded leaves, persistent woody female catkins, and darkening bark.
The bark has a long history in European folk medicine, where it was regarded principally as an astringent, febrifuge, hemostatic, and tonic. Modern phytochemical research has identified abundant phenolic compounds and diarylheptanoids and has demonstrated antioxidant and anti-inflammatory activity in laboratory and experimental models. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/36235365/))
Traditional uses:
* Astringent for diarrhea and intestinal complaints
* Treatment of wounds, ulcers, and inflamed skin
* Traditional treatment of fever
* Reduction of bleeding and hemorrhage
* Traditional treatment of swelling, inflammation, and rheumatic complaints
The bark has historically been described as astringent, cathartic, febrifuge, emetic, hemostatic, and tonic. Decoctions were also used for swelling, inflammation, and rheumatism. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/22424456/))
Historical use:
* European folk medicine used the bark as an astringent and febrifuge
* Bark decoctions were used for wounds, swelling, inflammation, and rheumatism
* Fresh bark was historically described as emetic
* Alder bark was used traditionally for hemostatic preparations
* Indigenous North American traditions also made medicinal use of *Alnus* species; Ojibwa records include bark and root preparations for bloody stools, anemia, and difficult childbirth
The latter traditions should not be assumed to refer exclusively to *A. glutinosa*, since North American Indigenous medicine frequently employed native *Alnus* species rather than European black alder. Historical ethnobotanical records nonetheless demonstrate the broader medicinal significance of alder. ([npshistory.com](https://www.npshistory.com/publications/indu/ethnobotany.pdf))
Parts used and method of use:
* Bark — principal medicinal material
* Leaves and catkins — occasionally used in traditional preparations
Used as:
* Decoction of the bark
* Infusion of bark or leaves
* External wash or compress
* Gargle or mouth rinse
Use in healing (modern herbal practice):
* Traditional external treatment of minor wounds and irritated skin
* Traditional astringent for inflamed or weeping tissue
* Traditional use for diarrhea and intestinal complaints
* Traditional use for inflammatory and rheumatic conditions
* Traditional use for fever and general convalescent toning
There is currently little high-quality human clinical evidence establishing efficacy for these traditional indications. Modern research is principally pharmacological and phytochemical. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/36235365/))
Pharmacology and biochemistry:
* Oregonin and other diarylheptanoids
* Tannins and other polyphenolic compounds
* Flavonoids and phenolic acids
Mechanisms:
* Polyphenols and diarylheptanoids provide substantial antioxidant activity in experimental systems
* Phenolic constituents and diarylheptanoids appear to suppress inflammatory signaling, including effects on TNF-α
* Tannins contribute astringent activity and may help explain traditional topical and gastrointestinal applications
Oregonin is particularly abundant in black alder bark extracts; one study found it constituted approximately 75% of the identified diarylheptanoid fraction. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/36235365/))
Overall profile:
A tannin- and polyphenol-rich traditional astringent tree with experimentally demonstrated antioxidant and anti-inflammatory properties. Its historical medicinal reputation is substantial, but modern clinical evidence remains limited.
Common dosage:
* Bark decoction: Traditional preparations vary considerably; no standardized modern therapeutic dose has been established
* Bark infusion: Traditionally prepared as a mild astringent tea; no evidence-based oral dosage is established
* External bark decoction: Traditionally applied as a wash or compress; concentration varies by preparation
* Gargle/mouth rinse: Mild bark or leaf infusion used traditionally; swallow as little as possible
Because modern clinical dosing standards are lacking, historical quantities should not be treated as established therapeutic doses.
Safety factors (including side effects):
* High-tannin preparations may cause gastrointestinal irritation, nausea, or constipation
* Internal use should be approached cautiously because standardized safety and dosing data are lacking
* Avoid medicinal use in pregnancy and breastfeeding unless directed by a qualified healthcare professional
* Individuals with known allergy to alder pollen or other Betulaceae plants should exercise caution
* Long-term internal use has not been adequately studied and should not be assumed to be safe
First aid / adverse reaction response:
* Gastrointestinal irritation or nausea: Discontinue use and seek medical advice if symptoms are severe or persistent
* Constipation: Discontinue or reduce use and maintain adequate hydration
* Suspected allergic reaction: Discontinue exposure; seek urgent medical attention for breathing difficulty, facial swelling, or collapse
* Suspected poisoning or severe adverse reaction: Contact a poison-control centre or seek urgent medical attention
Drug interactions:
* Tannins may reduce absorption of some orally administered medicines and minerals
* Theoretical interaction with iron supplements is possible because tannins can bind iron and reduce its absorption
* Concurrent use with other strongly astringent herbs may increase gastrointestinal effects
* No well-established clinical drug-interaction profile has been demonstrated for medicinal black alder preparations
Horticultural requirements:
* USDA / Canadian zone: Approximately 4–8; *A. glutinosa* is documented in Canadian cultivation and naturalization, including Ontario
* Soil pH: Approximately 5.0–8.0; tolerates acidic through neutral soils
* Light requirements: Full sun to partial shade
* Moisture: Moist to wet soil; highly tolerant of periodic flooding
* Other notes (growth habit, harvest timing, etc.):
* Fast-growing deciduous tree, commonly reaching approximately 12–18 m
* Female catkins become woody and remain on the tree after maturity
* Seeds mature and disperse primarily in autumn
* Naturally associated with wetlands, floodplains, stream margins, marshes, and wet woodland
* Propagation is primarily by seed; young trees transplant relatively readily
* Like other alders, it forms nitrogen-fixing associations with *Frankia* bacteria and can improve nitrogen availability in suitable soils
North Carolina Extension describes black alder as a rapidly growing tree tolerant of wet, infertile, and occasionally flooded soils and places it in USDA zones 4a–7b. ([plants.ces.ncsu.edu](https://plants.ces.ncsu.edu/plants/alnus-glutinosa/))
Sampling of clinical reports / studies:
* No substantial modern clinical trial evidence has established black alder bark as an effective treatment for diarrhea, wounds, rheumatism, fever, or other traditional indications.
* Experimental research on *A. glutinosa* stem bark demonstrated significant antioxidant activity and effects on TNF-α production, providing a possible biochemical basis for traditional anti-inflammatory applications. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/22424456/))
* A 2022 phytochemical study identified diarylheptanoids as predominant constituents of the bark extract, with oregonin particularly abundant, and demonstrated antioxidant, anti-inflammatory, and anti-angiogenic activity in experimental models. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/36235365/))
* Ethnobotanical evidence documents medicinal use of alder bark and roots among Indigenous peoples of North America, although the relevant records often concern native *Alnus* species rather than *A. glutinosa* specifically. ([npshistory.com](https://www.npshistory.com/publications/indu/ethnobotany.pdf))
* Overall assessment: Black alder has a strong European ethnomedicinal tradition as an astringent, hemostatic, febrifuge, and anti-inflammatory plant. Its bark contains a particularly rich mixture of tannins, phenolics, and diarylheptanoids, and laboratory research supports antioxidant and anti-inflammatory activity. However, there is not yet sufficient human clinical evidence to establish standardized therapeutic uses or dosing.
Educational Use Only: The information presented on this page is provided for educational, historical, and informational purposes only. ArdNemeton na Tuatha and Bhùth Draoi do not provide medical advice. Always consult your physician and pharmacist before using any herb, mushroom, supplement, or botanical product for medicinal purposes. Traditional uses described herein do not constitute medical claims.
