A simple tissue is made of only one type of cells. Tissues of same kinds compose simple tissue. Simple tissues are of three types, namely
Parenchyma: Characteristics of parenchyma tissue are as follows:
- Cells are almost uniform in length, breath and depth.
- Cells are round, oval or polygonal in shape.
- Cell wallls are evenly thick.
- Cells are living and contain sufficient protoplasm.
- There may have intercellular spaces between adjacent cells.
Chlorenchyma: 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.
- Chlorenchyma manufactures food materials.
- They store reserve food.
- They help, in transporting the food materials.
- Parenchyma in the epidermis act as a defensive organ.
Position: Usually pith, pith rays, epidermis and most of the cortex are made of this tissue.
Sclerenchyma: Characteristics of Sclerenchyma are as follows:
Cells elongateq and the ends are pointed.
Cell walls being lignified become thick and the thickness is uniform. Mature cells are dead and without nucleus and protoplasm.
In transverse section they are polygonal.
To give mechanical strength to different organs of the plant is the main function.
Some dead cell may store excretory substances of plants.
Sometimes it forms hard outer wall to protect the inner soft portion, e.g. seeds of coconut and date-palm
Position : They are present in cortex, phloem and pericycle.