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 deglupta flower buds contain stamens and pistil and are usually pollinated via bee. After fertilization, the flower capsule becomes a woody fruit, known as a gum nut, which contains the seeds. The unique multi-hued bark is the most distinctive feature of the tree. Patches of outer bark are shed annually at different times, showing a bright green inner bark. This then darkens and matures to give blue, purple, orange and then maroon tones. The previous season’s bark peels off in strips to reveal a brightly colored new bark below. The peeling process results in vertical streaks of red, orange, green, blue,