This book examines how plants interact with the environment and how they adapt to it. The first part deals with abiotic, natural environmental factors: light, ultra violet radiation, chilling and freezing, high temperatures, drought, flooding, salt, and trace metals in the environment. The second part addresses anthropogenic factors; that is, the environment created for plants by humans. It also examines allelochemicals, herbicides, polyamines, air pollutants, carbon dioxide, radioisotopes, and fire.