Resin secretory structures and yield of frankincense

Frankincense, a gum-resin, has been tapped from Boswellia papyrifera trees for centuries but information on the resin secretory structures is virtually absent. Tolera et al. examine tangential and radial sections of bark and wood samples from Ethiopian trees and find that resin canals form a three-dimensional network within the inner bark, with the resin-conducting and producing network on average limited to the inner 6.6 mm. The density of non-lignified axial resin canals decreases and the density of lignified resin canals increases from the vascular cambium towards the outer bark. In light of these findings, they suggest ways in which tapping methods could be improved to reduce labour and to be less harmful to the trees.