The Geography of Phytochemical Races

2 1 Introduction
It is useful to mention at this point a few citations from the earlier literature that
might be of interest to readers. Historical aspects of secondary metabolite distributions
were commented upon by Ralph Alston and Billie Turner in their groundbreaking
book Biochemical Systematics published in 1963. The general topic of
geographic patterning was revisited by Ralph Alston (1967) in a comprehensive
review. Soon thereafter, Tom Mabry (1973) reviewed the chemistry of geographic
races. Prof. Otto Gottlieb (1986) discussed microchemical evolution, including
geographic and ecological aspects of the subject, and reviews on other aspects of
chemical geographic patterns were treated by the present author (Bohm 1998a, b),
the fi rst being a more general discussion and the second a more specialized one
focusing on evolutionary relationships of island plants. All of these provide detailed
citation lists.
Information presented in this review appears under fi ve major headings: examples
within continents; examples involving glacial refugia and postglacial migrations;
examples involving oceanic disjunctions; examples involving island species; and
examples that exhibit north–south (polar) disjunctions. In many cases, larger taxa
have representatives that could fi t into two or more categories; hence, the assignments
to some sections are quite arbitrary. For example, species of Chrysosplenium
occur in eastern Asia; eastern, western, and boreal North America; northern Europe;
and in extreme southern South America. It is also worth bearing in mind the idea
that all plant distributions have been infl uenced to a greater or lesser extent by glaciation,
and that assigning an example to a particular category may be seen by some
readers as arbitrary.