Plants were of paramount importance to early man who depends upon them as sources of food, shelter, clothing, medicine, ornament and tools. This module also includes plants and their environment (hydrosphere, lithosphere and atmosphere). Today it is known that, in addition to their practical and economic values, green plants are indispensable to all life on Earth: through the process of photosynthesis. With the increased complexity of civilization human life has become more dependent on plants as will revealed by the superficial study of economically important plants.