The evolutionary chronicle of plant life on the Earth. Understanding of this history is largely based on knowledge of extant plants, but the fossil record is playing an increasingly important role in refining and illuminating this picture. Study of deoxyribonucleic acid (DNA) sequences has also been revolutionizing this process in recent years. In spite of a remarkably improved situation, controversy over interpretation of the available data can be expected to continue. The molecular data (largely in the form of DNA sequences from several genes) summarized below have been demonstrated to be highly correlated with other information.