Ever since I was a botany graduate student in the 1940s, I have been fascinated and
bothered by the field that is usually called historical plant geography. Wulff (1943) accurately
depicted the state of the field at that time, and a perceptive resurvey (Stott 1981) shows it has
changed little since then in basic concepts or methods. These were largely developed
during the nineteenth century as biogeographers came to recognize that spatial distributions
required explanation by both present and past processes of dispersal and environmental …