Flavonoids and affinities of some North American lupines

Seventy-three taxa of the genus Lupinus in North America have been studied for their flavonoid constituents. In all, 56 compounds were isolated and either partially or totally characterized. Flavonoid types encountered were flavones, C-glycoflavones, isoflavones, flavonols, and, tentatively, flavanones. Further structural modifications seen were O-methylation, O-glycosylation at a variety of positions and acylation of several of the flavonoid glycosides. Principal-components analysis was performed on (i) presence–absence data of individual compounds with consideration given to relative concentrations and (ii) presence–absence of the types of flavonoid structures. Several groupings of taxa emerged from these analyses based upon the presence of unique compounds or combinations of compounds. In a number of these groups the chemical affinities paralleled morphological affinities closely. In all, 10 groupings were seen. Lupinus diffusus, a simple-leaved taxon from southeastern United States, stood apart from all groups.