Theophrastus, who was born at Eresus on Lesbos (now in Greece), attended the Academy at Athens as a pupil of Plato. After Plato's death he joined Aristotle and became his chief assistant when Aristotle founded the Lyceum at Athens. On Aristotle's retirement Theophrastus became head of the school. The school flourished under him and is said to have numbered two thousand pupils at this time.

Of Theophrastus's many works, his nine-volume Enquiry into Plants is considered the most important. This is a systematically arranged treatise that discusses the description and classification of plants and contains many personal observations. A second series of six books, the Etiology of Plants, covers plant physiology. Theophrastus appreciated the connection between flowers and fruits and, from his description of germination, it is seen that he realized the difference between monocotyledons and dicotyledons.

Many of Theophrastus's pupils lived in distant regions of Greece and he encouraged them to make botanical observations near their homes. This practice probably helped him to conclude that plant distribution depends on soil and climate. Theophrastus was the first to invent and use botanical terms and is often called ‘the father of scientific botany’.