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.
A tissue is a mass of similar or dissimilar cells performing a common function. The body of a vascular plant is composed of dermal tissue, Ground tissue and Vascular tissue. Dermal Tissue (Skin). Dermal Tissue is protective in function. Basing on its origin, it is classified into two types Epidermis and Periderm.Epidermis: This is the primary surface tissue of the entire plant.he body of a vascular plant is composed of dermal tissue, Ground tissue and Vascular tissue. Dermal Tissue (Skin). Dermal Tissue is protective in function. Basing on its origin, it is classified into two types Epidermis and Periderm.