Micromorphological Traits of Balcanic Micromeria and Closely Related Clinopodium Species (Lamiaceae).

Dario Kremer,Mirko Ruščić,Danijela Stešević,Faruk Bogunić,Daniella Ivanova,Vladimir Ranđelović,Edith Stabentheiner,Dalibor Ballian,Valerija Dunkić,Eleni Eleftheriadou,Vlado Matevski

doi:10.3390/plants10081666

Abstract

A study of the trichomes types and distribution and pollen morphology was carried out in nine Micromeria taxa (M. cristata ssp. cristata, M. cristata ssp. kosaninii, M. croatica, M. graeca ssp. graeca, M. graeca ssp. fruticulosa, M. juliana, M. kerneri, M. longipedunculata and M. microphylla) and five closely related Clinopodium species (C. dalmaticum, C. frivaldszkyanum, C. pulegium, C. serpyllifolium and C. thymifolium) from the Lamiaceae family of the Balkan Peninsula. By scanning electron microscope, non-glandular trichomes, peltate and capitate trichomes were observed on the calyx, leaves and stem of the studied species. Two subtypes of capitate trichomes were observed in Micromeria species: subtype 1 (consisting of a basal epidermal cell and an elliptically shaped head cell) and subtype 2 (consisting of a basal epidermal cell, two to three stalk cells and a round head cell). In Clinopodium species, three types of capitate trichomes were observed: subtype 1, subtype 3 (consisting of a basal epidermal cell, a short peduncle cell, and a single round head cell), and subtype 4 (consisting of a basal epidermal cell, a stalk cell, and an elongated head cell). These results support the recent transfer of Micromeria species from the section Pseudomelissa to the genus Clinopodium.

Highlights

IntroductionMany of species belonging to this family are aromatic and medicinal plants due to the presence of glandular trichomes that produce essential oil
Non-glandular trichomes, peltate trichomes, and four subtypes of capitate trichomes were observed on the aerial parts of the Micromeria and Clinopodium taxa examined
NG trichomes, peltate trichomes and capitate trichomes of subtype 1 were observed in both Micromeria and Clinopodium taxa

Summary

Introduction

Many of species belonging to this family are aromatic and medicinal plants due to the presence of glandular trichomes that produce essential oil. One of the plant groups in this family is the genus Micromeria. According to Briquet [2], Killick [3] and Greuter et al [4], it is considered part of the indistinctly defined “Satureja” complex. This opinion is slowly being abandoned today. According to Bentham [5], Micromeria species form a separate genus and this opinion prevails today [6,7]

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Conclusion