THE SYSTEMATIC AND EVOLUTIONARY SIGNIFICANCE OF EXUDATE FLAVONOIDS IN AEONIUM

Leaf exudates of 32 species of Aeonium were examined for the presence of flavonoids. Thirty two flavonoids were detected in exudates of half of the species. The flavonoids were identified as methyl ethers of kaempferol, 6-hydroxykaempferol, quercetin, myricetin and scutellarein. The distribution of the exudate flavonoids is mostly in agreement with infrageneric sectional classifications based on morphological and molecular characters. The combination of kaempferol 3,7-dimethyl ether and quercetin 3,7-dimethyl ether is characteristic of section Aeonium. Myricetin methyl ethers are restricted to section Goochia and section Petrothamnium. Section Leuconium, section Canariense and section Patinaria are particularly poor in exudate flavonoids. 6-Hydroxyflavonoids occur in leaf waxes of six species belonging to sections Goochia, Canariense, Chrysocome and Pittonium, probably as a result of inheritance of this feature from a common ancestor. The presence of exudate flavonoids shows weak correlations with habitat and the presence of glandular hairs.