Olibanum, "the frankincense of ancients," is obtained from the members of the genus Boswellia mainly Boswellia carterri Birdw and Boswellia frereana Birdw and a dozen other species of Boswellia such as Boswellia bhaudarjiana Birdw, Boswellia papyrifera (Del.) Hochst, Boswellia sacra Flueckiger. The Boswellia species are small trees or shrubs, three to six meters high, which grow in rough and inhospitable arid mountainous regions at an altitude of 1000 to 1800 meters, the favourite areas being northeast Africa and southern Arabia.
On the other hand, Boswellia serrata Roxb, botanically differentiated into two varieties (viz., var. serrata with serrata and pubescent leaves and var. glabra with entire, glabrous leaves) is known as the Indian olibanum tree. This belongs to the same genus as the tree which provides the true frankincense or olibanum of commerce. Boswellia serrata is distributed and constitutes almost pure forests in many places; reliable statistics as to the exact area of this tree under cultivation is lacking.
The Boswellia tree contains physiological, schizogenous gum-oleoresin pockets on the bark. When the bark is incised, a white emulsion exudes which dries into globular, pear or club shaped tears. Depending on the size of the tree, it may be tapped in more than one place. Collection is carried out every fortnight or so. Usually only the exudate that settles on the wood is gathered; what flows down the stem accumulates and is scrapped off only annually; this material is regarded as an inferior or impure form.