Plant Tissue

Lab – 4 -
Plant Tissue
Tissue: Groups or masses of cells that are alike in origin , structure and function. Tissues classified in to:
1- Meristematic tissue: consists of a group of immature cells which remains in a continuous state of division. The cells may be rounded , oval or polygonal in shape, they are always living and thin-walled. Usually the intercellular spaces are not found among these cells .
2- The permanent tissue: are those in which growth has stopped either completely or for a time as sometimes they again become meristematic partially or wholly. The cells of these tissues may be living or dead and thin walled or thick-walled . The thin-walled permanent tissues are generally living whereas the thick-walled permanent tissues may be living or dead.

Plant tissues are grouped into three main systems:
1- The ground tissue system is the most extensive. It makes up the bulk of the plant body.
2- The vascular tissue system contains two kinds of conducting tissues that distribute water and solutes through the plant body.
3- The dermal tissue system covers and protects the plant s surfaces.

Some tissues in these systems contain only one type of cell and are called simple. Others are complex, highly organized arrays of two or more types of cells.

Simple Tissues
Simple tissues are made up of only one type of cell and are called either parenchyma, collenchyma, or sclerenchyma.
1- Parenchyma is the most common tissue in ground tissue systems. It comprises most of a plant s soft primary growth.