Flavonoids and Affinities of Greyiaceae with a Discussion of the Occurrence of B-Ring Deoxyflavonoids in Dicotyledonous Families

Abstract

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 3-0-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. The South African endemic, monogeneric family Greyiaceae Hutchinson consists of three species, Greyia flanaganii H. Bolus, G. sutherlandii Hook. & Harv. and G. radlkoferi Szyszyl. Greyia sutherlandii, the Natal bottlebrush, and G. radlko- feri, the mountain bottlebrush, are small, shrub- by, deciduous trees that occur principally in the Drakenberg Mountains. They are very similar and tend to intergrade. Greyia flanaganii, limited in occurrence to the eastern Cape Province, dif- fers from the others in floral features and is evergreen (Steyn 1974; Dahlgren and van Wyk 1988).