It is a well-known fact that trees and plants are also living beings like humans. They need food, water and air for survival. It is interesting to know how they take their food.
Plants derive their food both from the earth and the air. If you minutely look at their roots, you will find that the ends of these roots are like fine fibres. We call them root-hairs. They absorb water and minerals and transport them upwards to the leaves through the trunk and the branches. It is the leaves which prepare the food.
The leaves have pores which are filled with air. They also have a green colouring matter called chlorophyll. This chlorophyll acts as a catalyst, and uses carbon of the carbon dioxide and the hydrogen of the water present in the leaves to make carbohydrates (sugars). In this process oxygen and water are given out which are excreted by the leaves of plants.
Sugar is further converted into starch. From these carbohydrates, the plant can build up complex substances as foods which it needs for its life and growth. These substances include proteins, juices, oils (fats) etc. The water from which the plants take hydrogen for photosynthesis contains dissolved minerals needed in building various parts of the plant body. These are chiefly the compounds of nitrogen, sulphur, phosphorous, sodium, calcium, magnesium, iron etc.
Food not immediately needed for growth is stored in the plant including its seeds, fruits, tubers or bulbs. This accumulated food in the seed is used in its germination.