Micromorphology, anatomy and volatile constituents of leaf in some Lamiaceae species

Abstract

The objective of this study is to determine the range of variation in certain micromorphological, anatomical and biochemical characters of leaf within three spontaneous Lamiaceae species: Hyssopus officinalis L. (from Montenegro Republic), Thymus comosus Heuff. and Ocimum basilicum L. (both from Romania) The research material was collected in anthesis stage of plant development. Anatomical characters of leaf epidermis were examined by light microscopy. Scanning electron microscopy was used to examine leaf surface and trichomes. The qualitative analysis of the volatile oils has been carried out using GC-MS. All examined species had bifacial heterofacial and amphistomatous leaf. The stomata are diacytic. The glandular hairs consist of one epidermic basal cell, a uni- or multicellular stalk and a uni- or multicellular secretory head. The non-glandular trichomes are simple, short or long, multicellular uniseriate. The variable micromorphological and anatomical characters of leaf are rather quantitative than qualitative, as follows: 1. the mesophyll thickness; 2. the density of stomata and trichomes; 3. the number and size of intercellular air spaces of spongy mesophyll. The volatile oils produced by the investigated species differ in their composition. The aromatic value and therapeutical efficiency of these products strictly depend on the moment of plant development, metabolic transformations and climatic conditions. Among the analyzed species, the main constituents of volatile oils are: thymol, carvacrol, β-cariophylene, germacrene D, δ-cadinol, linalool and methylchavicol.