Simple tissue: Three types of simple tissues occur in plants:

(a) Parenchyma (b) Collenchyma (c) Sclerenchyma

(a) Parenchyma: It is a simple, permanent living tissue which is made up of thin-walled cells. The cells of this tissue are oval, elongated, and loosely packed with large intracellular space. Their cell wall is made up of cellulose. Each cell encloses a large central vacuole, cytoplasm and a prominent nucleus.

The parenchyma tissue is present in soft parts of the plant such as cortex, pith, palisade and some parts of the flower.

Parenchyma tissue provides support to plants and also stores food. In some situations, it contains chlorophyll and performs photosynthesis.

(b) Collenchyma: It is a another type of simple permanent tissue which is found few layer below the epidermis of leaves and stem. The cells of this tissue are living, elongated and tightly packed with no inter-cellular space. The cells have small nucleus, large vacuoles and thin cell wall but irregularly thickened at the corners.

Collenchyma tissue provides flexibility to plants so that they can easily bend without breaking. It also provides mechanical support to plants.

(c) Sclerenchyma: It is a supporting tissue. It is the tissue which make plant hard and stiff.

Location: This tissue is present in stems, around vascular bundles, in the veins of leaves and in the hard covering of seeds and nuts.

Structure: The cells of this tissue are dead. They are long, elongated, narrow, thick walled and lignified. These consists of fibres and sclereids.

It provides strength to the plants and enables them to withstand various strains.