Boswellia sacra (commonly known as frankincense or olibanum-tree) is a tree in the Burseraceae family. It is the primary tree in the genus Boswellia from which frankincense, a resinous dried sap, is harvested. It is native to the Arabian Peninsula (Oman, Yemen), and northeastern Africa (Somalia).
This species of Boswellia is a small deciduous tree, which reaches a height of 2 to 8 m (6 ft 7 in to 26 ft 3 in), with one or more trunks. Its bark has the texture of paper and can be removed easily. It has compound leaves and an odd number of leaflets, which grow opposite to one another along its branches. Its tiny flowers, a yellowish white, are gathered in axillary clusters composed of five petals, ten stamens and a cup with five teeth. The fruit is a capsule about 1 cm (0.39 in) long. The new leaves are covered with a fine down.
Individual trees growing on steep slopes tend to develop some buttressing that extends from the roots up into the base of the stem. This forms a sort of cushion that adheres to the rock and ensures a certain stability.
B. sacra tolerates the most critical situations and often grows on rocky slopes and ravines, up to an elevation of 1,200 m (3,900 ft), mostly in calcareous soil. Boswellia sacra is abundant in Oman in arid woodland, on the steep, precariously eroding slopes in the mountains of Dhofar, but it is most prevalent in northern Somalia.
In Somalia, frankincense is harvested in the Sanaag and Bari regions: mountains lying at the northwest of Erigavo; El Afweyn District; Cal Madow mountain range, a westerly escarpment that runs parallel to the coast; Cal Miskeed, a middle segment of the frankincense-growing escarpment; Karkaar mountains or eastern escarpment, which lies at the eastern fringe of the frankinscence escarpment.
The trees start producing resin when they are about 8 to 10 years old.
The resin is extracted by making a small, shallow incision on the trunk or branches of the tree or by removing a portion of the crust of it. The resin is drained as a milky substance that coagulates in contact with air and is collected by hand.
Growing conditions vary significantly, affecting both tree development and resin produced. Trees in the narrow fog-laden zone where the desert meets Dhofar mountain range, a region known as the Nejd, grow extremely slowly and produce very high quality resin in large, white clumps. Omanis and other Gulf State Arabs consider this to be superior to all other resins produced in North and Northeast Africa, India, and Asia, and it is priced accordingly.
Recent arguing about the frankincense tree populations growth of prevalence rate. There are many initiatives taken from owners of the lands, and organizations like the international banks have invested in harvesting new trees and making protection tools for the regions where the trees are mostly growing. It has helped in the increase of the production of the resin.
Lehrbuch der pharmakognosie Flückiger Boswellia sacra.