Lenticel

A lenticel is an airy aggregation of cells within the bark of the stems and roots of gymnosperms and the non-monocot flowering plants, and rarely on the leaf-stem (rachis). It functions as a pore, providing a medium for the direct exchange of gases between the internal tissues and atmosphere, thereby bypassing the periderm, which would otherwise prevent this exchange of gases. The name lenticel, pronounced with an, derives from its lenticular shape. The shape of lenticels is one of the characteristics used for tree identification.