Les esters de l'acide caféique dans la chimiotaxinomie des Teucrium de la section polium (Lamiaceae)

Several species of the genus Teucrium section polium from the mediterranean region are difficult to identify because of their wide morphological variability. The relationship between the morphological variations and the distribution of caffeic acid esters was studied. The results show that the taxonomic value of these markers is different depending on the nature of the molecule. Ecological factors interfere with the presence of verbascoside (diglycoside) more than they do with those of stachyoside and T2 (triglycosides). The presence of these latter molecules confirms the close relationship between T. polium subsp. polium and T. capitatum. The stachyoside present in T. polium subsp. polium also allows the distinction, in overlapping areas, of intermediary forms to T. aureum subsp. aureum, in which it is absent. Poliumoside is a specific marker for the polium section. It is never found in the other sections, where it is replaced by teucrioside and chlorogenic acid.