The Sedgwick Prize for the best essay on a geological subject was instituted in memory of Adam Sedgwick, the geologist who introduced Darwin to geology in walking tours of north Wales, but later opposed his theories. One of its most eminent winners was A. C. Seward (1863-1941), then a young lecturer in botany at Cambridge. He combined the study of botany with geology in his research on what the age and location of fossilised flora can reveal about the climates of different geological periods. The author of the standard early twentieth-century textbook in the field, Fossil Plants for Students of Botany and Geology (1898-1919), he served as Professor of Botany at Cambridge, Master of Downing College and Vice-Chancellor of Cambridge University. This Sedgwick Prize essay sets out the state of knowledge in the field in 1892 and was the foundation of a lifetime's work in palaeobotany.