Flavonoids at the Subtribal Level

Abstract

In this chapter we examine flavonoid occurrence patterns at the subtribal level. Two problems plague us in our efforts to find patterns of flavonoids at this level. The first has been with us from the outset, but it appears to manifest itself most acutely in examining subtribes, namely, sampling error. There are vast gaps in our knowledge of flavonoid occurrence. All too often, for example, one encounters clades [in the treatments in Bremer (1994)] where none of the component genera has been examined chemically. The second problem arises from the smaller range of structural variation that may exist within any subtribe; there are simply fewer variables available for comparison purposes. The combination of fewer OTUs and a reduced range of structural variation precludes the use of sophisticated numerical methods. The discussions below, therefore, will be based on visual comparisons of flavonoid profiles presented in a series of tables. In a few instances we use frequency values when warranted by sample size.