Lipophilic exudates of Pteridaceae - chemistry and chemotaxonomy

A number of fern species, belonging to several genera of Pteridaceae, exhib it a more or less conspicuous farinose wax, which is mostly located on the lower leaf surface. Production of these waxes is often correlated with the presence of glandular trichomes. Particularly during the past two decades, a series of publications appeared on the chemical composition of these exud ates. The major components were found to be flavonoids (chalcones, dihydroc halcones, flavanones, dihydroflavonols, flavones, flavonols), some of them with a complex substitution pattern, including esters and C-methyl derivati ves, and even bisflavonoids. Diterpenoids and triterpenoids can also occur in such exudates. It is the purpose of this paper to survey the chemical co mposition of Pteridaceae exudates and their occurrence within the genera of the family. The chemotaxonomic significance of the flavonoid aglycones at the generic, specific and populational level is briefly discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.