What are the structure and functions of simple permanent tissue?

Permanent tissue is composed of cells that have lost the power of division. It is of three types: simple permanent tissue, complex permanent tissue, and special tissue.

Simple permanent tissues

A simple tissue is made up of similar types of cells forming a uniform homogenous mass of cells. They may be living or dead. The common examples are parenchyma, collenchyma, and sclerenchyma.

1. Parenchyma
   1. It consists of isodiametric, thin-walled living cells with intercellular space.
      
      
   2. Each cell is bounded by a cellulosic cell wall with a centrally located large vacuole and Peripheral cytoplasm having a nucleus.
      
      
   3. It is found almost in all parts of plants such as stem, root, leaf, flowers, and fruit.
      
      
   4. The main function is the storage of food material.
      
      
   5. It is modified into the following types based on specific functions such as
      
      • Prosenchyma
        
        
      • Chlorenchyma
        
        
      • Aerenchyma
        
        
      • Xylem Parenchyma
        
        
      • Phloem Parenchyma
        
        
        
2. Collenchyma
   
   
   1. It is simple non-lignified living mechanical tissue with or without intercellular spaces and originated from the ground meristem.
      
      
   2. It is polygonal, spherical, or elongated with pointed or rounded ends.
      
      
   3. The cell walls unevenly thicken and rich in pectin and hemicellulose.
      
      
   4. It is found in the hypodermis of the herbaceous stem and dicot leaf.
      
      
   5. It may contain chloroplast and perform photosynthesis.
      
      
   6. Depending on the deposition of pectin in an intercellular space collenchyma may be angular (stem of Tagetus), lamellar (stem of Helianthus) and Lacunar of tubular (e.g. stem of Curcurbita)
      
      
   7. It provides mechanical support to stem and provide flexibility of organs (e.g. tendrils)
      
      
3. Sclerenchyma
   
   
   1. It is a long, elongated cell with narrow and pointed ends.
   2. It is lignified and thick-walled dead cell that does not perform metabolism.
      
      
   3. It is developed either from procambium or from secondary parenchyma.
      
      
   4. It contains deposition of different types of lignin with pits.
      
      
   5. This is supporting tissue that withstands various strains which result from stretching and bending of plant organs without any damage.
      
      
   6. Most commonly, the sclerenchyma cells are grouped into fibers and sclereids.