To which of these countries is the frankincense tree not native?

The frankincense tree is not native to the United Arab Emirates.

'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.

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.