Frederick Orpen Bower (1855-1948) was a renowned botanist best known for his research on the origins and evolution of ferns. Appointed Regius Professor of Botany at the University of Glasgow in 1885, he became a leading figure in the development of modern botany and the emerging field of paleobotany, devising the interpolation theory of the life cycle in land plants. First published between 1923 and 1928 as part of the Cambridge Botanical Handbook series, The Ferns was the first systematic classification of ferns according to anatomical, morphological and developmental features. In this three-volume work Bower analyses the major areas of comparison between different species, describes primitive and fossil ferns and compares these species to present-day fern species, providing a comprehensive description of the order. Volume 3 describes, analyses and classifies extant species of ferns.