# Plant Monograph: Cedar
**Name of plant:**
Cedar
**Catch phrase (Carmina Gadelica or traditional invocation if available):**
**“Ancient cedar, keeper of the evergreen flame, stand beside us in strength and protection.”**
No specific Carmina Gadelica invocation for North American cedar has been identified. Cedar has, however, profound ceremonial and medicinal importance among many Indigenous peoples of North America. **“Cedar” is a common name applied to several unrelated trees**, so the species should always be identified before medicinal use.
**Family:**
Cupressaceae
**Genus and species:**
*Thuja occidentalis* L. — Eastern white cedar / arborvitae
**Other names:**
* Eastern white cedar
* Northern white cedar
* White cedar
* Arborvitae
* Tree of life
* American arborvitae
* Cedar
* French: thuya occidental
* Ojibwe: *giizhik* / *giizhag* (names vary by dialect and orthography)
**Brief introduction:**
Eastern white cedar is an evergreen conifer native to eastern and central North America, particularly associated with wetlands, limestone habitats, rocky shorelines and boreal or mixed forests. It is readily recognized by its flattened sprays of scale-like foliage and small cones.
The tree has extraordinary cultural importance in many Indigenous traditions. Cedar has been used for medicine, purification, protection, construction, clothing, bedding and ceremonial purposes. It is important to distinguish these traditions from the unrelated Mediterranean **cedars (*Cedrus* species)** and from western red cedar (*Thuja plicata*).
The name **arborvitae**, meaning “tree of life,” arose from the tree's historical use by French explorers who learned of its antiscorbutic properties from Indigenous peoples.
**Traditional uses:**
* Used traditionally as a medicinal tea or decoction for respiratory complaints.
* Used as a source of vitamin C in traditional preparations and historically against scurvy.
* Used externally for skin complaints and wounds.
* Used in bathing, steaming and cleansing practices.
* Used ceremonially for purification, protection and connection with the natural world.
**Historical use:**
* Indigenous peoples of northeastern North America used white cedar extensively for medicine and practical materials.
* Indigenous knowledge of cedar's antiscorbutic properties was communicated to Jacques Cartier's expedition during the winter of 1535–1536.
* Early European accounts describe cedar preparations being used to treat scurvy among Cartier's crew.
* The tree became known in European botanical medicine as *Arbor vitae*, “tree of life.”
* Cedar wood, bark and foliage were historically used for canoes, baskets, roofing, clothing, cordage and household objects.
**Parts used and method of use:**
* Young foliage and tender twigs.
* Bark and wood, primarily for external, practical or ceremonial applications.
Used as:
* Dilute infusion or decoction of young foliage.
* External wash or compress.
* Steam or bathing preparation.
* Smoke, aromatic or ceremonial use of dried plant material, where culturally appropriate.
**Use in healing (modern herbal practice):**
* Historically used as a source of vitamin C.
* Traditionally used for respiratory congestion and coughs.
* Traditionally employed externally for minor skin complaints.
* Used in some herbal traditions as a warming or stimulating aromatic herb.
* Occasionally used in traditional preparations for menstrual or digestive complaints.
Modern medicinal use is limited by the safety concerns surrounding concentrated cedar preparations and **thujone**, and it should not be treated as a routine internal herbal tea without appropriate identification and dosage guidance.
**Pharmacology and biochemistry:**
* **Thujone** — a monoterpene ketone found in the essential oil.
* **Thujaplicins and related tropolones** — contribute antimicrobial and antifungal activity.
* **Vitamin C (ascorbic acid)** — particularly relevant to the historical antiscorbutic use of fresh foliage.
Mechanisms:
* Thujone affects neuronal GABA-A receptor signalling and, at sufficiently high concentrations, can produce CNS excitation and seizures.
* Essential-oil constituents demonstrate antimicrobial and antifungal activity in laboratory studies.
* Vitamin C supports collagen synthesis and normal antioxidant and immune functions.
**Overall profile:**
Eastern white cedar has a **strong historical and ethnobotanical record**, particularly for its vitamin-C-containing foliage and extensive Indigenous applications. Its essential oil is pharmacologically active but potentially toxic because of thujone. **Concentrated essential oil and internal medicinal doses require considerable caution and should not be confused with the traditional use of dilute preparations.**
**Common dosage:**
* **Fresh foliage infusion:** traditional preparations have varied considerably; no universally established medicinal dose should be assumed.
* **Dried foliage tea:** medicinal dosing should be professionally guided because thujone content varies by plant and preparation.
* **External infusion/wash:** dilute preparations may be used externally as traditionally appropriate.
* **Essential oil:** **not recommended for internal use** because of toxicity concerns.
**Safety factors (including side effects):**
* Cedar foliage and essential oil contain thujone and other compounds capable of producing toxicity at sufficiently high doses.
* Excessive internal consumption may cause nausea, vomiting, abdominal pain, dizziness, agitation or neurological symptoms.
* **Pregnancy is a major contraindication** to medicinal internal use because cedar preparations may stimulate uterine activity and have historically been associated with abortifacient use.
* Essential oil can irritate skin and mucous membranes and should never be applied undiluted.
* High-dose or prolonged internal use may produce neurological toxicity, including seizures.
**First aid / adverse reaction response:**
* **Skin irritation:** remove the preparation and wash the area thoroughly with soap and water.
* **Eye exposure:** flush immediately with plenty of clean water and seek medical attention if irritation persists.
* **Nausea, vomiting, dizziness or abdominal pain after ingestion:** discontinue use and contact a poison-control centre or healthcare professional.
* **Confusion, severe agitation, tremors or seizures:** seek emergency medical attention immediately.
* **Suspected essential-oil poisoning:** do not induce vomiting; contact a poison-control centre or emergency service.
**Drug interactions:**
* Thujone-containing preparations may theoretically interact with medications affecting the central nervous system.
* Because thujone can promote neuronal excitation at high concentrations, caution is appropriate with drugs affecting seizure threshold.
* Concentrated preparations may theoretically interact with other hepatotoxic or neuroactive substances.
* Medicinal internal use should be discussed with a healthcare professional when prescription medicines are being taken.
**Horticultural requirements:**
* **USDA / Canadian zone:** Approximately USDA zones 2–7, depending on provenance and cultivar.
* **Soil pH:** Approximately 5.5–7.2; adaptable to moderately alkaline soils.
* **Light requirements:** Full sun to partial shade.
* **Moisture:** Prefers consistently moist soil but can tolerate moderately dry conditions once established.
**Other notes (growth habit, harvest timing, etc.):**
* **Growth habit:** Dense, slow- to moderately-growing evergreen tree, commonly reaching 10–20 m in natural conditions, with numerous ornamental cultivars.
* **Flowering/fruiting:** Small inconspicuous reproductive structures produce small elongated cones during the growing season.
* **Harvest timing:** Young foliage has historically been gathered during the growing season; fresh foliage contains vitamin C.
* **Habitat:** Swamps, wet forests, limestone cliffs, rocky shorelines and mixed woodland throughout eastern and central North America.
* **Propagation/cultivation notes:** Propagated from seed or cuttings. Tolerates pruning well and is widely cultivated as a hedge and ornamental tree. Requires adequate moisture during establishment.
**Sampling of clinical reports / studies:**
* **Historical clinical evidence:** Accounts from Jacques Cartier's 1535–1536 expedition document Indigenous knowledge of white cedar being used to treat scurvy.
* **Pharmacological study:** Laboratory research demonstrates antimicrobial activity among several cedar essential-oil constituents.
* **Phytochemical study:** *Thuja occidentalis* contains thujone, other monoterpenes, tropolones, flavonoids and vitamin C.
* **Ethnobotanical evidence:** Extensive Indigenous ethnobotanical records document medicinal, ceremonial, nutritional, construction and material uses.
* **Overall assessment of evidence:** **Strong historical and ethnobotanical evidence; meaningful pharmacological evidence for individual constituents, but limited modern clinical evidence for most medicinal applications. The plant's traditional importance is substantial, while concentrated internal preparations carry genuine toxicity concerns.**
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.