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The chemical composition of the essential oil (analysed by GC and GC-MS), the types and distribution of trichomes and pollen morphology (analysed by scanning electron microscopy) were investigated in two closely related species, Micromeria kerneri Murb. and Micromeria juliana (L.) Benth. (Lamiaceae) from Southeast Europe as a contribution to their taxonomy. The essential oil of M. kerneri was characterized by a high concentration of oxygenated sesquiterpenes, with caryophyllene-oxide as the major compound. Caryophyllene-oxide was also the major component of the essential oil of M. juliana from all localities, except from Mt Krivošije (Montenegro), where piperitone oxide was the major constituent. Non-glandular trichomes, peltate trichomes, and two types of capitate trichomes (type 1 composed of one basal epidermal cell, and one head cell with subcuticular space; type 2 composed of one basal epidermal cell, two stalk cells, and one head cell with subcuticular space) were observed on leaves, the calyx and on the stem. Pollen of both species had six apertures (hexacolpate) set in the equatorial pollen belt (zonocolpate) and showed medium reticulate ornamentation. Multivariate analysis (PCA and UPGMA) of essential oil components clearly separated the investigated M. kerneri and M. juliana populations, and confirmed the opinion that they are different taxa. On the other hand, micromorphological traits between these species were the same. Nevertheless, definitive conclusions about the taxonomic relationships among these species will require genetic analysis., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A study on the types and distribution of trichomes, pollen morphology, chemical composition of essential oil (analyzed by GC-FID and GC/MS), and the content of macroelements (Na, K, Ca, and Mg) and trace elements (B, Fe, Cu, Mn, Zn, Al, Pb, Cr, Cd, Ni, Hg, and As) analyzed by ICP-AES (=inductively coupled plasma atomic emission spectroscopy) was conducted on Micromeria croatica (Pers.) Schott. Non-glandular trichomes, peltate trichomes (typical hairs of Lamiaceae), small capitate trichomes (composed of one basal epidermal cell and one head cell), and larger capitate trichomes (composed of one basal epidermal cell, two to three stalk cells, and one head cell with subcuticular space) were observed on leaves, stems, the calyx, and corolla. Pollen of M. croatica had six apertures (hexacolpate) which were set in the equatorial pollen belt (zonocolpate) and showed medium reticulate ornamentation (hetrobrochate type). The essential oil contained from 27 to 39 constituents, the most representative of which were caryophyllene oxide and E-caryophyllene. Among the investigated macroelements, the content of K was highest (8730-10080 mg/kg). The content of trace elements ranged from 0.12 mg/kg (Cr) to 78.00 mg/kg (Fe), while the content of Cd, Ni, Hg, and As were lower than the limit of quantification., (Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.)

Types and distribution of trichomes, chemical composition of the essential oil, as well as contents of phenolic compounds were studied in four Balcanic Clinopodium L. species (family Lamiaceae), namely C. dalmaticum (Benth.) Bräuchler et Heubl, C . pulegium (Rochel) Bräuchler, C . serpyllifolium (M. Bieb.) Kuntze, and C . thymifolium (Scop.) Kuntze. Non-glandular trichomes, peltate trichomes, and three types of capitate trichomes were observed on the leaves, calyces, and stems. In general, 62 different essential oil compounds were identified: 21 from C . dalmaticum , 31 from C. thymifolium , 36 from C. serpyllifolium , and 37 from C. pulegium . The essential oil of all species was characterized by the high content of oxygenated monoterpenes (66.2–79.6%), with dominant menthane type compounds, such as menthone, pulegone, piperitenone, and piperitenone oxide. Total polyphenols (TP), tannins (T), total flavonoids (TF), and total phenolic acids (TPA) were determined spectrophotometrically. The lowest levels of these compounds were found in C. serpyllifolium (3.83%, 0.88%, 0.39%, and 2.91%, respectivelly), and the highest in C. thymifolium (TP, 7.40%) and C. pulegium (T, 1.78%; TF, 0.57%; TPA, 6.59%). [ABSTRACT FROM AUTHOR]