During the 7th century the power of the Eastern Roman (Byzantine) Empire was challenged by the Sassanids of Persia, who invaded Egypt in 616. They were expelled again in 628, but soon after, in 642, the country fell to the Arabs, who brought with them a new religion, Islam, and began a new chapter of Egyptian history.
Bark comprises all the tissues outside the vascular cambium of a vascular plant. The majority of the bark of woody plants develops from three meristems: the vascular cambium that gives rise to the secondary phloem, the phellogen that gives rise to the cork and dilatation meristem that produces parenchyma cells to avoid cracking when the axis increases in diameter.
In temperate regions, where trees are winter deciduous, students learn to identify species based on bark (and winter bud) characteristics, and bark types are useful taxonomic characters in other habitats as well. Often more than one term can be used to describe the bark of a tree or shrub.The young stems often have a different appearance than larger branches, and branches do not resemble the bark found at the base of a trunk. The following are some of the terms used to describe bark. 1  Ring bark.ften more than one term can be used to describe the bark of a tree or shrub. The young stems often have a different appearance than larger branches, and branches do not resemble the bark found at the base of a trunk.