Study of plant anatomical characteristics and essential oil composition of Hungarian Salvia species

We studied the anatomical characteristics, such as the structure and position of glandular and covering trichomes of four Salvia species (Lamiaceae): S. officinalis L., S. sclarea L., S .pratensis L. and S. nemorosa L. The composition of the essential oil in the various species and their plant organs: leaf, calyx and petal was also investigated. The plants used for this study were cultivated in the garden of the Ecological and Botanical Research Institute of the Hungarian Academy of Sciences. The microscopical studies were carried out using Axioscop apparatus. Extraction of essential oils was carried out by the methods of the Hungarian Pharmacopoea. The essential oil composition was analysed by a gas chromatographic method. Each organ of the Salvia species investigated contains glandular and covering trichomes. The labiate-type glandular trichomes are characteristic and other glandular trichomes composed of a unicellular head are also present. On the calyx and petal numerous glandular and covering trichomes can be found. Their structure is similar to those of S. officinalis. A few of the glandular trichomes are on the petals, too. A lot of whip-like trichomes are present, but conical unicellular trichomes are rare. The big covering trichomes, having short basal cells and a sharp terminal cell, are characteristic for the leaf of S. sclarea. Some conical covering trichomes are also found. The leaf of S. pratensis is poor in trichomes. There are rarely multicellular covering and glandular trichomes with a unicellular head. Comparing the essential oil composition of the fresh and dried plant organs of the four Salvia species, differences exists only in S. officinalis. The dominant components are sesquiterpenes: α-humulene and caryophyllene in the fresh leaf-oil. In dried leaf oil, the monoterpene thujone isomers were characteristic. The qualitative oil composition of the three organs does not differ, but the percentage occurrence of the components is variable. The thujone isomers are dominant (17-20 %) in the leaf- and calyx-oil, but there is only 5,9 % in the petal-oil. The main component of petal-oil is the pharmacologically active β-pinene (24,4 %). For the composition of S. pratensis oil, β-caryophyllene and γ-muurolene are characteristic. Their ratio in the calyx and petal-oils are similar, but in the leaf-oil, this is reversed. The structure of the covering trichomes and the percentage occurrence of the oil components provides a good basis for the differentiation of Salvia species.