FLAVONOIDS AND AFFINITIES OF GREYIACEAE WITH A DISCUSSION OF THE OCCURRENCE OF B-RING DEOXYFLAVONOIDS IN DICOTYLEDONOUS FAMILIES

The leaf surface flavonoid profiles of all three species of Greyia, the sole genus in Greyiaceae, have been shown to consist of a mixture of flavones, flavanones, dihydroflavonols and flavonols, several of which lack B-ring substitution. Several of these compounds were reported as components of Escallonia, a genus thought by some to be related to Greyiaceae. The vacuolar flavonoid profile consists of kaempferol and quercetin 3-O-mono- and diglycosides. Whereas the vacuolar flavonoids are not significant taxonomically, the identification of B-ring deoxyflavonoids as major components of leaf surface exudates of Greyia adds to the list of characters by which Greyiaceae and Melianthaceae can be distinguished. The widespread occurrence of B-ring deoxyflavonoids in dicot families reduces their usefulness for assessing relationships at higher taxonomic levels.