What to know about Thuja occidentalis (arborvitae) before using it medicinally

Thuja occidentalis, commonly known as arborvitae, is a herb rich in health-promoting properties, including antimicrobial and antifungal compounds that can boost the immune system and improve overall health.

This versatile herb is also prized for its ornamental and landscaping value, with conical shape and fragrant foliage making it a popular choice for gardens and parks. From a botanical standpoint, Thuja occidentalis is a member of the cypress family (Cupressaceae), with scale-like leaves and small, spherical cones that are often used in floral arrangements.

Historically, Thuja occidentalis has been used in traditional medicine for centuries, with references to its healing properties dating back to the early American colonists and indigenous populations.

This article explains the medicinal, horticultural, botanical, and historical aspects of Thuja occidentalis.

What are the medicinal properties of Thuja occidentalis?

Thuja occidentalis helps with various health issues, including fever reduction, respiratory problems, and skin conditions, such as eczema and dermatitis, due to its anti-inflammatory and antimicrobial properties.

The active constituents responsible for the medicinal properties of Thuja occidentalis include terpenes, particularly thujone and bornyl acetate, as well as flavonoids and lignans, which contribute to its antimicrobial, anti-inflammatory, and antioxidant activities.

The parts of the plant most used for medicinal purposes are the leaves, bark, and twigs, which are rich in essential oils and contain the active constituents responsible for its medicinal properties, making them effective in treating various health conditions.

Improper use of Thuja occidentalis may lead to side effects such as gastrointestinal upset, dizziness, and allergic reactions, particularly when taken in large quantities or for extended periods, highlighting the need for careful dosage and monitoring.

Precautions to take when using Thuja occidentalis medicinally include consulting a healthcare professional, especially for pregnant or breastfeeding women, as well as individuals with liver or kidney disease, and using it in conjunction with other medications only under medical supervision.

What are the horticulural aspects of Thuja occidentalis?

Thuja occidentalis grow best in full sun to partial shade with well-drained soils and a slightly acidic to neutral pH. They prefer temperatures between 65°F and 75°F (18°C and 24°C). This evergreen can tolerate drought but performs best with regular watering.

When planting Thuja occidentalis, choose a location with good air circulation to prevent disease. Plant the tree at the same depth as it was in the nursery, with the root flare visible above the soil. Mulch around the base to retain moisture and suppress weeds. Water thoroughly after planting.

Harvesting Thuja occidentalis can be done for foliage, cones, or as a specimen plant. Prune in late winter or early spring to maintain shape and size. Cones can be harvested in fall after they turn brown. Foliage can be harvested as needed for craft or decorative purposes.

Common pests and diseases affecting Thuja occidentalis include bagworms, spider mites, and root rot. Bagworms are the most significant threat, feeding on the foliage and causing damage. Regularly inspect the tree for signs of these pests and diseases, and take action promptly if you notice any issues.

What are the botanical aspects of Thuja occidentalis?

Thuja occidentalis is a coniferous evergreen tree with scale-like leaves, 1-2 cm long, that are dark green on top and pale underneath. The leaves are densely packed on short shoots, and the bark is grayish-brown and fibrous.

The taxonomic classification of Thuja occidentalis is as follows: Kingdom: Plantae, Clade: Angiosperms, Clade: Gymnosperms, Order: Cupressales, Family: Cupressaceae, Genus: Thuja, Species: T. occidentalis.

There are several variants of Thuja occidentalis, including 'Smaragd' (a compact, slow-growing cultivar), 'Nigra' (a darker-leaved cultivar), and 'Techny' (a hybrid between Thuja occidentalis and Thuja plicata). These variants differ in growth habit, leaf color, and size.

Thuja occidentalis is native to eastern North America, ranging from Canada to the northeastern United States. It is commonly found in moist woods, along streams, and in wetlands. It has been naturalized in other parts of the world, including Europe and Asia.

The life cycle of Thuja occidentalis typically lasts 100-150 years. The plant starts as a seed, germinating in the fall and growing as an evergreen shrub or tree. It reproduces by producing cones, which contain seeds that can be dispersed by wind, water, or animals.

What are the historical aspects of Thuja occidentalis?

Thuja occidentalis is an evergreen tree with a long history of use in medicine, craft, and spiritual practices. Native Americans used the leaves and bark for fever reduction, rheumatism, and as a diuretic. European settlers adopted these uses and added the tree's wood to their homes for its durability.

In mythology, arborvitae is associated with the Ojibwe people, who considered the tree a symbol of good health and longevity. The tree's distinctive, twisted branches were said to resemble the figure of a wise elder. This connection has been maintained through oral tradition and cultural practices.

Arborvitae has been imbued with symbolic meanings across cultures. In European folklore, the tree's ability to thrive in poor soil and withstand harsh winters made it a symbol of resilience and perseverance. In some Asian cultures, the tree's fragrance is associated with spiritual growth and enlightenment.

The earliest written records of arborvitae use date back to the 16th-century French explorer Samuel de Champlain, who documented its medicinal properties. The Swiss botanist Leonhard Fuchs described the tree's wood and resin in his 1542 botanical guide, De Historia Stirpium. These texts highlight the importance of the tree in early European exploration and colonization.

Arborvitae has been depicted in various historical artifacts, including wood carvings and prints from 18th-century European settlements in North America. These artworks demonstrate the tree's significance in early American art and culture. Examples can be found in the collections of institutions such as the British Museum and the Metropolitan Museum of Art.