Tree tissue. It protects the trunk against the elements, disease, animal attack and fire. It is perforated by a large number of fine breathing pores called lenticels, through which oxygen diffuses. Bark is continually replaced by a living layer of cells called the cork cambium or phellogen. The London plane ("Platanus × acerifolia") periodically sheds its bark in large flakes. Similarly, the bark of the silver birch ("Betula pendula") peels off in strips. As the tree's girth expands, newer layers of bark are larger in circumference, and the older layers develop fissures in many species. In some trees such as the
Eucalyptus rigidula Eucalyptus rigidula Eucalyptus rigidula, commonly known as stiff-leaved mallee, is a mallee that is native to Western Australia. The mallee typically grows to a height of . The bark of the tree is smooth and white-grey brown in colour and peels in ribbony strips at the base. It blooms between December and April producing inflorescences with white flowers. The bark is smooth and powdery with no pith of bark glands. The disjunct, glossy, green or yellow-green adult leaves have a lanceolate to broad lanceolate shaped blade that is basally tapered. The thick concolorous blade is in length and wide. The