Canarium schweinfurthii

Basic Information

Common Name: Canarium schweinfurthii
Scientific Name: Canarium schweinfurthii
Native Habitat: Primarily found in tropical Africa, spanning a wide range from West Africa (including countries like Nigeria, Ghana, Cameroon) across to East Africa (such as Uganda, Tanzania, Kenya) and extending southwards into Angola, Mozambique, and Zambia. It typically grows in lowland evergreen rainforests, moist deciduous forests, riverine forests, and sometimes extends into gallery forests or savannas, often associated with water bodies.

History / Discovery / Cultivator

The history of Canarium schweinfurthii, often known as the African elemi or bush butter tree, is deeply intertwined with the traditional cultures and ecosystems of tropical Africa. Unlike plants whose history is marked by a singular European “discovery,” the story of Canarium schweinfurthii is one of ancient use and cultural significance among the people indigenous to its vast native range. For centuries, possibly millennia, various communities have relied on this tree for a multitude of purposes, long before it was formally catalogued by Western science.

The botanical name, Canarium schweinfurthii, was given in honor of Georg Schweinfurth, a German botanist and explorer who conducted extensive research in Northeast Africa during the latter half of the 19th century. His work contributed significantly to the scientific understanding and classification of African flora. While Schweinfurth’s name is attached to the species in the Linnaean system, the tree itself was a well-established and vital resource for local populations. Its fruits, resembling large olives or dates, have long been a source of food, particularly for their oily pulp, which gives rise to the common name “bush butter tree.” The resin, known as African elemi, has been traditionally harvested for medicinal purposes, incense, and as a sealant or adhesive. Timber is also utilized locally.

Throughout its distribution, Canarium schweinfurthii is not typically found in large, formalized plantations like many commercial crops. Its cultivation is often integrated into traditional agroforestry systems or managed within natural forest environments. Farmers and villagers protect naturally occurring trees on their land or plant seedlings in a more informal manner, recognizing their value for food, income, and other products. This traditional management has helped maintain the species within its ecological niche. Efforts towards more structured cultivation and domestication have been explored in recent decades by agricultural researchers and development organizations, aiming to enhance fruit yield, quality, and post-harvest processing, as well as to promote its economic potential for rural communities. However, it remains largely a tree of the forest and the traditional farm rather than a globally traded commodity crop on the scale of coffee or cocoa.

The cultural significance of the tree is reflected in local names and uses across different ethnic groups. It is a tree deeply embedded in the landscape and livelihood of millions in tropical Africa. Its history is less about a single point of discovery and more about a long, ongoing relationship between humans and a valuable natural resource, a relationship that predates formal botanical classification and continues to this day through traditional harvesting and informal cultivation practices. The scientific naming by Schweinfurth simply brought this already important species into the global botanical record.

Plant Care Summary

Botanical Insights

Adaptations

Canarium schweinfurthii exhibits several adaptations that allow it to thrive in its tropical forest and savanna-edge environments. Its large size, growing up to 40 meters tall with a substantial trunk and buttress roots in older specimens, provides stability in potentially unstable forest soils and access to upper canopy light. The species is known for producing aromatic resin, a characteristic of the Burseraceae family it belongs to. This resin, often called African elemi, is exuded when the bark is injured and serves as a protective mechanism against pests and diseases, helping to seal wounds. The production of relatively large, oily, and nutritious fruits is a key adaptation for reproduction, attracting a variety of animals (birds, bats, mammals) that consume the fruit and disperse the seeds, aiding in the spread of the species throughout its range. Its adaptation to varying light conditions, from full sun in open areas to partial shade in forest understories (especially when young), contributes to its wide distribution.

Propagation Methods

Propagation of Canarium schweinfurthii is most commonly achieved through seed. Seeds are typically collected from ripe fruits, cleaned of pulp, and sown relatively fresh, as viability can decrease over time. Germination rates can vary, and pre-treatment methods like soaking may sometimes improve results. While seed propagation is the primary method in traditional settings and for establishing new stands, vegetative propagation techniques have been explored, particularly in efforts to domesticate and improve the species. These methods can include grafting, budding, or air layering, which allow for the cloning of desirable traits from superior trees (e.g., high fruit yield, better fruit quality, faster growth). However, vegetative methods can be more technically challenging and may require specific environmental conditions (like high humidity) for success compared to simple seed sowing.

Toxicology

Based on extensive traditional use, Canarium schweinfurthii is generally considered non-toxic, particularly regarding its fruit. The fruit is widely consumed by humans and various animals throughout its native range, either fresh or processed (often soaked in hot water to soften the pulp). The resin (elemi) is also used traditionally for medicinal purposes and as incense, suggesting a lack of severe toxicity in small quantities, though direct ingestion of large amounts of raw resin is unlikely and not recommended. Scientific literature and ethnobotanical studies do not report instances of toxicity from consuming the fruit, leaves, or bark. Therefore, for common household pets and humans, ingestion of parts of the Canarium schweinfurthii tree is not known to cause significant toxic effects. As with any plant, individual sensitivities can exist, but it is not listed among commonly toxic plants.

Common Problems

Pests:

• Stem borers (Various insect larvae)
• Leaf-eating insects (Various caterpillars, beetles)
• Scale insects (Can occasionally infest young growth or stressed trees)

Diseases:

• Root rot (Typically associated with poor drainage or waterlogged conditions)
• Anthracnose (Fungal disease causing leaf spots or fruit lesions, often in humid conditions)

Other:

• Poor fruiting: Can be caused by lack of appropriate pollinators, insufficient light, or young tree age.
• Slow initial growth: Seedlings can be slow to establish and grow in their early stages.
• Nutrient deficiencies: Yellowing leaves or poor vigor can indicate lack of essential nutrients, especially in poor soils.

Rarity & Value

Rarity:

Within its native tropical African range, Canarium schweinfurthii is not considered rare in the ecological sense, being relatively widespread in suitable habitats. However, it can be considered ‘rare’ in cultivation outside of Africa, or even in formalized commercial cultivation within Africa compared to major cash crops. Its rarity in global horticulture or forestry markets stems from it not being a focus of large-scale international trade or domestication efforts until relatively recently. Seed availability outside Africa is limited, and establishing the tree requires specific tropical conditions, further reducing its presence globally. Variegated or unusual forms, which can drive rarity in ornamental plants, are not typically sought or found in this species.

Value:

The value of a Canarium schweinfurthii tree is primarily assessed based on its potential yield and quality of fruit and resin, particularly in its native range. Large, mature trees with consistent, high fruit production are highly valued by local communities for food and income. The quality and quantity of the aromatic resin also contribute to the tree’s value, as the resin is used in traditional medicine, incense, and sometimes exported. Timber has local value. Outside of Africa, the value is less established, often related to botanical interest or potential future agroforestry applications rather than immediate market value for products. Factors affecting market value where traded might include tree size (for timber or potential yield), apparent health, and provenance (origin), though a standardized global market valuation for Canarium schweinfurthii does not widely exist.