Differences in essential oil production and leaf structure in pheno-types of damiana(turnera diffusa willd.

Plants of damiana(Turnera diffusa Willd.) are important to industry and traditional medicine in semi-arid climates. Although all populations are wild, no reports have been made previously of their different phenotypes. Here, we investigated various micromorphological characteristics and the levels of essential oils in two phenotypes. Oils were extracted from fresh leaves via hydrodistillation and analyzed by gas chromatography-mass spectrometry. Morphological analyses were conducted under a stereoscopic microscope and with a scanning electron microscope. In all, 56 compounds were identified, enabling us to distinguish separate phenotypes. DL1 plants mainly contained 1,8-cineole, 10-epi y eudesmol, and guaiol; whereas those of DL2 primarily constituted ß-pinene, ß-caryophyllene oxide, cadinene, and α-cadinol. These two phenotypes also differed in their morphologies, with DL1 leaves showing elevated essential oil concentrations, but lacking trichomes. In contrast, the DL2 plants had lower contents of essential oils but did possess trichomes on their abaxial and adaxial leaf surfaces. This documentation of individual damiana phenotypes is the initial process toward validating the quality of essential oils from this species as well as inherent structural variations.