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Permanent Tissues

Permanent tissues

Permanent tissues are the ones that have lost the power of cell division and have attained a permanent shape, size, and function. They can be two types – simple permanent tissues and complex permanent tissues.

1 Simple permanent tissues

  • Simple tissues are made up of similar permanent cells that carry out the same function or similar set of functions. Simple permanent tissues are of three types – parenchyma, collenchyma, and sclerenchyma.

1.1 Parenchyma

  • It consists of thin-walled living cells that have intercellular spaces between them, and their cell wall is made of cellulose. It serves the function of food storage, absorption, lateral conduction, photosynthesis, providing buoyancy, section, etc.

1.2 Collenchyma

  • It consists of refractile non-lignified living cells that possess pectocellulose thickening in specific areas of their walls. It provided mechanical strength as well as the flexibility to young dicot stem, petiole, and leaves. It often contains chloroplasts for photosynthesis.

1.3 Sclerenchyma

  • Sclerenchyma consists of dead cells with hard and extremely thick secondary walls sue to uniform deposition of lignin. Sclerenchyma is two types, fibres and sclereids. The fibres occur in all those parts where mechanical strength is required. Sclereids are found in walls of nuts and seed coat in the walls of nuts and seed coat of legumes.

                                   Figure: Various types of simple tissues

                      (a) Parenchyma (i) transverse section (ii) longitudinal section

                      (b) Collenchyma (i) transverse section, (ii) longitudinal section

                       (c) sclenchyma (i) transverse section , (ii) longitudinal section

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