The Geography of Phytochemical Races

252 6 Oceanic Islands
Fig. 6.3 Compounds 525–535, a thiophene derivative and fl avonoids from Hawaiian Bidens
that exhibited profi le differences among populations. The fl avonoid chemistry of
B. torta was also shown to be somewhat more complex than the other taxa, in that
it exhibited a more highly developed capacity for fl avonoid O-methylation resulting
in the accumulation of a suite of okanin mono-, di-, tri-, and tetramethyl ether
derivatives, for example, [535], (McCormick et al., 1984).
Perhaps the most noteworthy aspect of the fl avonoid study, however, was the high
level of variation exhibited across the range of collections. Simply put, there was no
relationship between taxonomic position and fl avonoid profi le. Differences between
individuals within the same population (even adjacent plants!) often exceeded differences
between other pairs of taxa. The level of variation present within this group
of taxa represents one of the most extreme cases of fl avonoid variation in the present
author’s experience [see Bohm (1987) for a review of fl avonoid variation].