Simple Tissues

There are three basic types named for the type of cell that makes up their composition: (1) parenchyma tissue, (2) collenchyma tissue, and (3) sclerenchyma tissue.

Parenchyma tissue

Parenchyma cells form parenchyma tissue. Parenchyma cells are the most abundant of cell types and are found in almost all major parts of higher plants. These cells are basically sphere-shaped when they are first made. However, these cells have thin walls, which flatten at the points of contact when many cells are packed together. Generally, they have many sides with the majority having 14 sides. These cells have large vacuoles and may contain various secretions including starch, oils, tannins, and crystals. Some parenchyma cells have many chloroplasts and form the tissues found in leaves. This type of tissue is called chlorenchyma. The chief function of this type of tissue is photosynthesis, while parenchyma tissues without chloroplasts are generally used for food or water storage. Additionally, some groups of cells are loosely packed together with connected air spaces, such as in water lilies, this tissue is called aerenchyma tissue. These types of cells can also develop irregular extensions of the inner wall which increases the overall surface area of the plasma membrane and facilitates transferring of dissolved substances between adjacent cells. Parenchyma cells can divide if they are mature, and this is vital in repairing damage to plant tissues. Parenchyma cells and tissues comprise most of the edible portions of fruit.