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Tissues Class 9 Science - Plant Tissue - Simple Permanent Tissue

Tissues Class 9 Science - Plant Tissue - Simple Permanent Tissue When meristematic cells lose their ability to divide, it gets converted to permanent tissue. To form permanent tissue, cells undergo the process of differentiation. It is a process in which cells take up different shapes and sizes, and form other type of cells. Simple permanent tissue : Simple permanent tissues are made up of same type of cells. It is classified into parenchyma, collenchyma and sclerenchyma. Parenchyma : Structure : Cells in parenchyma are alive and contains thin wall. They are loosely held with each other and have large intercellular spaces. Functions: Cells in parenchyma tissue is responsible for food storage and providing support to plant. If cells in this tissue contains chlorophyll, then it is able to prepare food for plants, by process of photosynthesis. Such parenchyma cell are known as chlorenchyma. In aquatic plants, air is filled in intercellular spaces of parenchyma cell; this allow them to keep floating in water. Such parenchyma cells are known as arenchyma. Collenchyma: Structure : Cells in collenchyma tissue are alive, elongated, and are irregularly thick with less intercellular space. They are found below the epidermis. Function : Collenchyma provides flexibility in plants. Hence, it becomes easy for plants to bend without breaking. Sclerenchyma : Structure : Cells in sclerenchyma are dead. They are long, narrow and have thick walls. Walls are composed of lignin which makes it hard. They are present in stem surrounding vascular bundle, in leaf veins, in seed covering, etc. Function : Makes plant hard and provides strength. Epidermis : Structure : Epidermis is the outermost layer of plant. It is made up of single continuous layer of cells without intercellular spaces. Most of these cells have flattened structure. The outer wall of cell is thicker than the inner wall. Epidermis have kidney shaped cells called stomata. Epidermis covers the entire outer surface of plant body. Functions : Epidermis plays an important role in protection of plants from mechanical injury, entry of fungi, etc. Epidermis on roots shows development of hair like structures, which helps in absorption of water and nutrients from the soil. In desert area, epidermis of plants are comparatively thicker to prevent water loss. Stomata present in the epidermis, is essential for exchange of gases in plants; and it is responsible for transpiration i.e. loss of water from the plant body.