The frankincense tree (Boswellia genus) is known for its aromatic resin, historically used in incense, perfumes, and traditional medicine. However, its leaves also have notable characteristics and applications that are often overlooked.
Physical Characteristics of Frankincense Tree Leaves
Frankincense tree leaves, particularly from species like Boswellia sacra, are compound, made of multiple smaller leaflets arranged in an odd-pinnate pattern. These oblong leaflets typically measure 10 to 25 centimeters long and 5 to 8 centimeters wide.
The leaves are a consistent dark green. New leaves often have a fine, downy covering. While the upper surface can appear somewhat glossy, the underside may be slightly hairy. Frankincense trees are deciduous, shedding their leaves during certain periods, which is important for their survival in arid environments.
The Frankincense Tree and Leaf Adaptations
Frankincense trees thrive in challenging arid and semi-arid environments, including rocky slopes and ravines in Oman, Yemen, and the Horn of Africa. These trees, often growing to heights of 2 to 8 meters, have developed specific leaf adaptations to endure harsh conditions with limited water and intense sunlight. Their ability to grow directly from rocks, anchoring themselves with cushion-like swellings, highlights their resilience.
A key leaf adaptation is their deciduous nature, allowing the tree to shed foliage during prolonged dry periods. This mechanism helps conserve water by reducing transpiration. This seasonal shedding ensures the tree’s survival in drought-prone habitats.
Uses and Benefits of Frankincense Tree Leaves
The leaves of the frankincense tree have been traditionally utilized for various purposes, extending beyond the well-known resin. In some traditional medicine systems, extracts from the leaves have been explored for their potential benefits. Some studies indicate the use of Boswellia leaf extracts to help manage blood glucose levels.
Frankincense leaves also contain aromatic compounds, and essential oils can be extracted from them. These leaf essential oils contain components such as alpha-pinene, which is often the dominant compound, along with others like alpha-thujene and myrcene. While the resin is primarily known for its anti-inflammatory properties due to boswellic acids, the leaves contribute to the overall phytochemical profile of the tree.
Leaves and Frankincense Resin Production
The frankincense resin is primarily harvested from the bark of the Boswellia tree, not the leaves. When the bark is incised, the tree exudes a milky white sap that hardens into “tears” upon exposure to air. This resin is a complex mixture of volatile oils, gums, and non-volatile compounds, including boswellic acids.
Although the leaves are not the source of the commercial resin, they do contain their own aromatic compounds, contributing to the overall scent profile of the living tree. Essential oils derived from the leaves, while distinct from resin essential oils, still share some common monoterpenes. Boswellic acids, the primary active components of frankincense resin known for their anti-inflammatory effects, are typically found in the woody parts and resin, and are not present in significant amounts in steam-distilled frankincense leaf essential oils.