Different Kinds of Permanent Tissue

Permanent tissue are of three types:

1. Simple tissue,

2.Complex tissue and

3.Secretory tissue

Simple tissue: Tissues of same kinds compose simple tissue. Simple tissues

are of three types:

1.Parenchyma

2. Collenchyma

3. Sclerenchyma:

      Ø Parenchyma :Characteristics of parenchyma tissue are as follows:

1.Cells are almost uniform in length, breath and depth.

2.Cells are round, oval or polygonal in shape.

3.Cell wallls are evenly thick.

4.Cells are living and contain sufficient protoplasm.

There may have intercellular spaces between adjacent cells. Permanent – tissues that Thin cell wall contain chlorophyll are called Chlorenchyma. The chlorenchyma of leaf IS called Messophyll. Parenchymatous tissues with large air spaces In aquatic plants are Aerenchyma.

      Ø Functions:

1.Chlorenchyma manufactures food materials.

2.They store reserve food.

3.They help ,in transporting the food materials.

Parenchyma in the epidermis act as a defensive organ.

      Ø Position: Usually pith, pith rays, epidermis and most of the cortex are made of this tissue.

      Ø Collenchyma: Characteristics of collenchyma tissues are as follows:

1.Cells are to some extent elongated. '

2.Cells are living with protoplasm.

3.Cell wall is unevenly thick, thickness is greater at eorners of the cells.

4.There may have intercellular spaces between adjacent cells.

      Ø Functions:

1.     Cells with chlorophyll manufacture food.

2.     It gives mechanical strength ' to the growmg organ.

      Ø Position: It is found under the epidermis, in the petioles and veins of leaves and in the flower stalks.

      Ø Sclerenchyma: Characteristics of Sclerenchyma are as follows:

1.Cells elongateq and the ends are pointed.

2.Cell walls being lignified become thick and the thickness is uniform. Mature cells are dead and without nucleus and protoplasm.

3. In transverse section they are

polygonal.

      Ø Functions:

1.To give mechanical strength to different organs of the plant is the main function.

2 .Some dead cell may store excretory substances of plants.

3.Sometimes it forms hard outer wall to protect the inner soft portion, e.g. seeds of coconut and date-palm

      Ø Position : They are present in cortex, phloem and pericycle. 

      Complex tissue: Complex tissue is composed of more than one kind of cells. They are two types:

1. Xylem tissue

2. Phloem tissue.

     Ø Xylem tissue: Xylem tissue consists of four types of cells:

1.Tracheids

2.Vessels or Trachae

3.Xylem fibre

4.Xylem Parenchyma

      Ø Tracheids: Cells are dead, long with transverse ends, containing large vacuole. Cell walls are hard, strong. and lignified. Their main functions are to gIve mechanical strength and to supply water and dissolved minerals from root to the leaves.

      Ø Vessels or Trachaea: Cells are broad and short, placed end to end to form a

continuous hollow tube. Water and waterdissolved minerals are conducted from root to leaf by these cells.

      Ø Xylem fibre: These are sclerenchymatous cells. Their main function is to give

mechanical strength to the plant.

      Ø Xylem parenchyma: These are parenchymatous . cells. Functions of these cells are storage and conduction of food materials.

      Ø Functions of xylem tissue: Their functions are to give mechanical strength to the plant body, conduction of water, minerals and food materials and storage of food.

      Ø Phloem tissue: Phloem tissue consists of four types of cells:

1. Sieve tubes

2. Companion cells

3. Phloem fibres

4.Phloemparenchyma.

      Ø Sieve tube: These are elongate hollow cells placed end-to-end forming. a long tube. The partition walls between two adjacent sieve cells are perforated and known as sieve plate. In m4;iture sieve tube there is. no nucleus in the cell. Conduction of food, prepared in the leaves is its main function.

      Ø Companion cells: These are parenchymatous, narrow, elongated cells, and

are closely associated with the sieve tube. They have dense cytoplasm and a

large nucleus. Conduction with the sieve tube is done through the pores present

on the walls of these cells. They help the sieve tubes in conduction of food

materials.

      Ø Phloem fibre: These are Sclerenchymatous cells. They are also known as bast

fibre. Its function is to give mechanical strength.

      Ø Phloem parenchyma: These are parenchymatous cells. They help in storage

and conduction of food materials.

      Ø Function of Phloem tissue:

1.There main function is to conduct food materials, prepared in the leaves, to different parts of the plant.

2.They give mechanical strength to plant organ.

3.In case of necessity they store food materials.

      Ø Importance of Complex tissues:

In respect of physiological and economic aspects, complex tissues are of great importance.

Secretory tissue: Secretoy tissues are those tissues, which secrets various liquids, Resins, gums, rubber etc. are collected from secretory tissues. They are of two types: .

1.Laticiferous tissues

2.Glandular tissues.

Ø  Laticiferous tissue: Latex is a white, yellow or colourless liquid Carbohydrates, protein, gums, and fats etc. are mixed in Latex, Latex is found in various plants like;- Musa (KALA) Ficus (BOT), Hevea (RUBBER), Papiver (OPIUM), Calotropis (AKONDO), Alstonia (CHHATIM), Argement (SHIALKATA).

Ø  Glandular tissue: Honey, Enzymes, Gums, Resins, Oils etc. are usually found in the glandular tissues .