Beautiful portrait of Teak wood Bark is the outermost layers of stems and roots of woody plant. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. The inner bark, which in older stems is living tissue, includes the innermost area of the periderm. The outer bark in older stems includes the dead tissue on the surface of the stems. The outer bark on trees which lies external to the last formed periderm is also called the rhytidome.