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UE 27 Wt:, , > Tissue system: A group of tissues performing related function., On the basis of the structure and location, there are 3 systems- Epidermal, Ground &, Vascular., , I. Epidermal Tissue System / Covering (Epi°=upon, derma®=skin ), , = It forms the outer-most covering of the whole plant body., It comprises epidermis, stomata and epidermal appendages., , 1) Epidermis, , = It is the outermost protective layer of the plant body., , = Epidermis is usually single layered compactly arranged parenchymatous cells., , = The epidermis is covered with a waxy coating (cuticle). It is absent in roots., Function: Prevents the loss of water., , 2) Stomata, , = These are minute pores present in the epidermis of leaves., , = Each stoma is made of two bean-shaped guard cells in dicots. In monocots, the guard, cells are dumb-bell shaped., It regulates the opening and closing of stomata., , , , Stomata in dicot In monocot, = The cells seen near the guard cells are known as subsidiary cells., Stomatal pore + guard cells + subsidiary cells = Stomatal apparatus., Function: Gaseous exchange and transpiration