Plant Tissue

Plant Tissue

1. Meristamatic tissueConsists of actively dividing cells. Meristematic tissue of three types:

   • Apical meristem-Present at the growing tips of stems and roots. Its function is to increase the length of stems and roots.
   • Intercalary meristem- Present at the base of leaves or near the nodes. Its function is for the longitude growth of plant.
   • Lateral meristem- Present on the lateral sides of the stems and roots. Its function is to increase the thickness of stems and roots.

2. Permanent Tissue-Formed from meristematic tissues, the cells in the tissue loose the ability. Permanent tissues are divided into two categories

   • Simple permanent tissue- Consists of only one type of cells.
     • Parenchyma- Composed of unspecialised cells with relatively thin cell wall, large intercellular space, present in soft parts of the plants. Their main function is storage.
     • Collenchyma- Composed of living and elongated cells with cells walls and irregularly thickened at the corners. Very little intercellular space. It provides mechanical support and elasticity to plant. It helps in bending of leaves and stems
     • Sclerenchyma- Composed of long, narrow and thick walled cells. This tissue is made up of dead cells and there is no intercellular space. It cells are dead, present in seeds, nuts, husk of coconut, fibres of juice etc.
   • Complex permanent tissue- Made up of more than one type of cells.
     • Xylem- Conducts water and minerals from the roots to the different parts of plant. Composed of four different types of cells- tracheids, vessels, xylem parenchyma and xylem fibres.
     • Pholem- Conducts food material from the leaves to the different parts of the plants. Composed of four different types of cells- sieve tubes, companion cells, pholem parenchyma and pholem fibres.