Structural investigations of trichomes and essential oil composition of Salvia verticillata

Abstract.

Krstic L., Malencic Dj. and Anackov G. 2006. Structural investigations of trichomes and the essential oil composition of Salvia verticillata. Bot. Helv. 116: 159 – 168.

The morphology of glandular and non-glandular trichomes and the essential oil composition of Lamiaceae play an important role in the ecology of these species as well as for their industrial use; they may also serve as taxonomic criteria. We studied the trichome anatomy and essential oil composition of three wild-growing populations of Salvia verticillata in Serbia to determine how strongly these traits vary among and within Salvia species, and to evaluate their potential taxonomic or economic significance. Microscopic investigations of leaf and calyx indumentum revealed that S. verticillata has the same types of peltate and capitate trichomes as other Salvia species. In combination, however, the trichome characteristics of S. verticillata differed from previously examined Salvia species and might therefore help in species identification. The density of glandular trichomes differed among the three populations and was lowest in a dry steppe habitat, but trichome density also varied substantially among individual leaves within each population. The essential oil content (determined gravimetrically in n-hexane) ranged from 0.40% to 0.42% of dry mass. In total, 39 different oil components were identified using GC-MS. Oil composition varied considerably among the three populations. Only three of the 39 compounds were well represented (>0.1% of oil) in all three populations: The main component was germacrene D in two populations (48.0% and 24.6% of oil, respectively) but (E)- caryophyllene (10.2%) in the third. Low oil content and high variability in oil composition may restrict the industrial use of wild-growing S. verticillata plants.