Composition of the essential oil and micromorphology of trichomes of Teucrium salviastrum, an endemic species from Portugal

Abstract

The morphology, distribution and release mechanism of the glandular trichomes of Teucrium salviastrum Schreber were studied, along with the chemical composition of the essential oils. Peltate and capitate trichomes are present on both vegetative and reproductive organs. In this study, particular emphasis is given to the capitate trichomes with long multicellular stalks. These trichomes are very abundant, and the secretion material is released by cuticule rupture on the top of the head cells. Also noteworthy is the presence of peltate trichomes on the upper surface of the ovary. Although already described in some Lamiaceae, these trichomes have not been recorded previously on any other Teucrium species. The composition of the essential oil was studied using mainly GC and GC-MS. The oils isolated from leaves, collected during the flowering and post-flowering phases of the plant, as well as the oil isolated from the flower heads, exhibited a similar chemical composition. Nevertheless, the oils showed remarkable differences in composition when compared to those reported in the literature for the same species. The present study has shown that our oil consisted mainly of E-beta-farnesene (26.1-29.3%), E-caryophyllene (19.1-24.1%) and germacrene D (13.7-21.6%). The major compound of our samples, E-beta-farnesene, is reported for the first time for this species. Copyright © 2002 John Wiley & Sons, Ltd.