Question

What are the permanent tissues of the plants? Give their characteristics.

Answer 1

A permanent tissue is a group of cells in which growth has either stopped completely or for the time-being.

Permanent tissue if of two types: Simple permanent tissue and complex permanent tissue.

Simple permanent tissues:

• Simple tissues are tissues are composed of cells which are structurally and functionally similar. They are of three types, parenchyma, collenchyma and sclerenchyma.
  
  Parenchyma- These are rounded cells with thin cell walls, small nucleus and a large vacuole. It may store food, provide temporary support.
  
  Collenchyma- It is made up of cells which are elongated and the cell wall is thickened at the corners. It is a living tissue that acts as a mechanical tissue and provides mechanical support to young dicot stems.
  
  Sclerenchyma- Composed of long narrow cells, which are dead and have thick cell walls. It provides mechanical support.

Complex Tissue

• The complex tissues consist of more than one type of cells having a common origin.
  
• Xylem and phloem are both conducting tissues.

Xylem

• Xylem is a vascular and mechanical tissue.
  
• Xylem is a conducting tissue helps in unidirectional conduction of water and minerals, composed of cells (called elements) of four different types: Tracheids, vessels, xylem parenchyma and xylem fibres.

Phloem

• Phloem is complex permanent tissue that conducts bi-directional organic solutes or food materials from leaves to roots.
  
• Phloem is composed of four components or cells- sieve tubes, companion cells, phloem parenchyma, phloem fibres.