Plants are classified into two broad categories, vascular and non vascular. Planted have two systems of tubes for transportation of water and food. They are called vascular. Non vascular are those who are dry simple pants that lack the system of tubes for transporting water and food. Roots, stems, leaves, fruited, and seeds are the main parts of the plant. roots anchor a plant to the ground and the stem bears the buds leaves and flowers. Flowers are the ripened ovary of a flowering plant. There are three types of tissue systems in a plant. These are dermal, vascular and ground tissues. Dermal tissue is the plants protective covering. Vascular consists of xylem and phloem that transports water and nutrients between roots and shoots the ground tissue comprises the bulk of the primary plant body. There are four types of pollination. Entomophily, zoophhily, anemophily and hydrophilic. Process done by insects like bees is entomophily. Zoophhily is the process of pollination done by animals. Aemhily is pollination by wind. Hydrophily is done in water. Asexual reproduction. Occurs in plants without seeds or spores grafting budding, or by using cutting are the various methods of asexual reproduction. Through this method replica is created. Plants are useful to man in various ways. The oxygen that we breathe is released by the plants. It is the source of food for all the living things either directly or indirectly. They provide many things like paper, rubber, medicines clothes and various types of food too. Chlorophyll is a small pigment seen in the leaves. It provides the green color to the leaves. It absorbs blue and red portions of electromagnetic spectrum but fails to absorb the green colour. Hence green color of the leaves is seen.
Photosynthesis is a process that takes place . It is taking place in the mesophyl cells of the plant, these cells are spongy. It is the process that enables the plants to be the primary producer of food in the food chain. Starch is a basic food. Group for humans. It is the fuel. That gives energy foe many tasks that the human being has to do. Starch is stored by plants in stems, roots, leaves and fruits too. The first plants appeared on earth. About 450. Million years ago. There are 27,0000 kinds of plants on earth. Many appeared by the end of Devonian Period about three hundred sixty million years ago.
