Phylogeny and phytogeography

Biogeography is a useful tool for the phylogenist. Distribution patterns, past and present, can be most instructive in indicating possible relationships. This observation is true because the closest living relatives of a phyletically unplaced taxon are more likely than not to be found in the same or adjacent areas rather than on distant continents. However, this generalization must be used with caution for many plant groups possess great vagility and have spread rapidly into appropriate habitats over the earth. The largely Old World Pittosporales are described in some detail as a prime example of application of this dictum of geographic plausibility. Archaic dicotyledons of the Australasian and Asian regions are discussed as other examples of the dictum, as are a few North American taxa such as Simmondsia, Crossosomataceae, and Batis. Additional angiosperms are listed without discussion for both North and South America.