Why nare 'simple permanent tissues' called so?
The cells of permanent tissues do not have the ability to divide. These cells are already differentiated in different tissue types and is now specialized to perform specific functions. They are subdivided into two groups, viz, simple tissues consisting of cells which are more or less similar, e.g. epidermis, parenchyma, chlorenchyma, collenchyma, sclerenchyma and complex tissues consisting of different kinds of cells, e.g. xylem and phloem. So, simple permanent tissues are called so because the cells are similar and are differentiated.
A few layers of cells forms the basic packing tissue. This tissue is called parenchyma, A type of permanent tissue. It consists of relatively unspeciallised cells with thin cell walls. They are live cells. They are usually loosely packed and have large spaces between them. Then cholenchyma-this tissue provides support to plants and also stores food. In some situations, it contains chlorophyll and performs photosynthesis. Scalenchyma-this tissue makes plant hard and stiff. The cells of this tissue are dead. Example- bark of tree