DIFFERENCES IN FLAVONOID PATTERNS BETWEEN GENERA WITHIN THE VELLOZIACEAE

Detailed flavonoid analysis of seven representative species of Aylthon ia, Barbacenia, Burlemarxia and African and Madagascan Xerophyta have confirmed the paucity of surface flavonoids in these genera compared w ith Vellozia, where complex mixtures of lipophilic flavonoids are comm on. However, some simple flavonol O-methyl ethers including 6-methoxyk aempferol 3-O-methyl ether were found in small amounts on the leaf sur face of two Barbacenia species. In the subfamily Barbacenioideae, Aylt honia was distinguished from both Barbacenia and Burlemarxia in its va cuolar flavonoids by the presence of flavone mono-C-glycosides rather than flavone di-C-glycosides and Pleurostima is unique in lacking glyc oflavones but possessing 6-hydroxyflavones. Complex mixtures of flavon ol mono-O- and di-O-glycosides were found within the leaves of Barbace nia and Burlemarxia species, while only quercetin monoglycosides were detected in Aylthonia riedeliana. In Balbacenia conicostigma, the 3-ap iosylgalactosides and 3-apiosylglucosides of quercetin and isorhamneti n were characterized; the former two compounds were present also in Bu rlemarxia spiralis. In Xerophyta eglandulosa var. eglandulosa from Mad agascar an isomeric quercetin 3-apiosylglucoside occurred. The Madagas can Xerophyta species were distinguished from the African Xerophyta sp ecies by the absence of glycoflavones and presence of isorhamnetin gly cosides, while in X. dasylirioides quercetin 3-methyl ether and querce tin di- and trimethyl ethers were identified free within the leaf. Sim ilarly, in Barbacenia conicostigma four flavonol methyl ethers, as wel l as kaempferol and chrysoeriol occurred in the free state. However, X . retinervis from South Africa was exceptional in producing 6-C-methyl quercetin 3-methyl ether, chrysoeriol 7-glucoside and both flavone mo no- and di-C-glycosides within the leaf. The present results confirm t hat flavonoid patterns are useful in determining generic limits within the family.