Botany covers a wide range of scientific disciplines including structure, growth, reproduction, metabolism, development, diseases, chemical properties, and evolutionary relationships among taxonomic groups. Botany began with early human efforts to identify edible, medicinal and poisonous plants, making it one of the oldest branches of science. Nowadays, botanists study about 400,000 species of living organisms.
Modern botany traces its roots back more than twenty three centuries, to the Father of Botany, Theophrastus (c. 371–287 BC), a student of Aristotle. He invented and described many of the principles of modern botany. His two major works, Enquiry into Plants and On the Causes of Plants constitute the most important contribution to botanical science during antiquity and the Middle Ages, and held that position for some seventeen centuries after they were written.