Page 1 : On the basis of composi, Imposition per is iad, complex permanent tissues, Permanent tissues are classified in to simple permanent tissue and, , Simple permanent ti it, issues: i ts, homogeneous mass @ simple tissue is made up of only one type of cell forming a, , ‘Types of simple permanent tissues,, , Common type of simple permanent tissues are parenchyma, collencyma and sclerenchyma., , Parenchyma :- \s the most common type of simple permanent tissue. It is composed of living cells with, uniformly thin cell wall made up of only cellulose. Typical parenchyma cells are oval, spherical or polygonal in, shape. Usually a prominent nucleus is present , either at the centre or near the cell wall., , ‘Types of parenchyma- based on cell structure and function itis classified in to the following, , Simple parenchyma- from the ground tissue of the plant organs., , Chlorenchyam or assimilatory parenchyma- the parenchyma that contains large number of, chloroplast, which carries out photosynthesis., , c. Aerenchyma -is a type of parenchyma where the tissues have very large intercellular space which, store air., , Functions pf parenchyma, , a., b., , a. Storage of food and water, , b. Aerenchyma helps plants in floating and gaseous exchange., c. Chlorenchyma helps in photosynthesis, , d. Parenchyma is the main living tissues in plants, so it helps in regeneration and wound healing,, Collenchyma:-collenchyma is a type of simple permanent living mechanical tissue, The main differences, between parenchyma and collenchyma is the unevenly thickened primary walls seen in collenchyma,, Collenchyma usually found inthe hypodermal regions of cicote stems. These cells appear circular in cross, section., , Functions of collenchyma- It gives mechanical support, , a. Collenchyma can resist bending and stretching caused by winds, b. Collenchyma with chloroplast perform photosynthetic function, ¢._ It gives rise to phellogen during secondary growth., Sclerenchyma:- Is a simple permanent hard tissue adapted for mechanical functions. Sclerenchyma is dead at, maturity, The cells in sclerenchyma ae thickened uniformly and often lgnified, The cels of this tissue very, thick, and it vary size and shape. They are placed in two groups the fibers and sclereids,, , Sclerenchyma fibers Are elongated , spindle shaped with pointed tips. The cells are compactly arranged, without inter cellular spaces. The cell wall is very thick, lignified and pitted in sclerenchyma fibers. The, central cavity is highly reduced and known as lumen., , sclereids sclereids are short board, irregularly shaped cells of sclerenchyma tissues. Sclereids are dead, ‘ven mature, Depending upon shape and thickening sclrcids are of four types., , , , , , 4)Brachysclecids ~ these are isodiametnic or oval shaped. They are present in the pulp of fruit wall, coconut, shell etc.