In this part of the book we turn our attention toward general patterns and processes of evolution, although these issues have been dealt with to some extent in other chapters. In Chapter 11, Bruce Bohm provides the first review of distributions of plant secondary products in island ecosystems. Some workers have suggested (e.g., Carlquist, 1980) that in view of their probable defensive functions from fungi and insects, many compounds have, in the more open (and certainly different) habitats of oceanic islands, possibly undergone loss of diversity. That is, relaxation of predation pressure would surely lead to loss of defensive chemicals over many generations. Bohm's survey suggests the contrary. No obvious loss of compounds is seen when comparing chemical arsenals in island plants with continental relatives.

In Chapter 12, the theme of chromosomal stability in endemic plants of oceanic islands is continued by Stuessy & Crawford, that was initiated in Chapter 1 by Gerald Carr for the Hawaiian Islands. This new chapter extends Carr's observations for the Hawaiian Islands into the endemic angiosperm floras of the Juan Fernandez, Bonin and Galapagos Islands, as well as comparisons with the Canary Islands and the Queen Charlotte Islands. The Canaries have a complex geological history, are older relative to the other archipelagos and are very close to the source area in continental Africa. Much more cytological variation in certain genera is seen. On the Queen Charlotte Islands, which are essentially part of the Canadian continent separated only by vagaries of sea level, typical continental levels of chromosomal variation are revealed.