Due to climate extremes and limited natural resources, especially water, we can expect increased demand in the future for species that can better tolerate climate extremes such as drought. One potentially valuable horticultural species is the endemic species of the Dinaride Mountains Micromeria croatica (Pers.) Schott (family Lamiaceae). It grows in the crevices of carbonate rocks, extending from an altitude of 150 m to more than 2000 m. This study aims to provide additional insight into the genetic and morphological diversity of this endemic species, focusing on valuable horticultural traits. To achieve this goal, morphological and molecular analyses were performed on ten natural populations. Through STRUCTURE and PCoA analyses, ten M. croatica populations were placed into western and eastern genetic groups, with several individuals from western populations assigned to the eastern group and vice versa. These atypical individuals assigned to the new genetic group by BAPS analysis indicate gene flow between western and eastern populations. Similarly, an analysis of molecular variance revealed fewer genetic differences than within studied populations. Both PCA and CANDISC analysis based on eleven morphological traits largely confirmed the existence of two slightly different genetic groups. Two populations containing plants with the most flowers per shoot, one with white-flowered individuals, one with the roundest leaves, and one with the narrowest leaves proved to be the most horticulturally valuable. The genetic and morphological variability found should be a sufficient basis for the potential selection of M. croatica populations and individuals for horticultural purposes.

Simple Summary The genus Sorbus (whitebeams, rowans, and service trees) encompasses forest trees and shrubs characterised by exceptional diversity resulting from the interplay of polyploidisation, hybridization, and apomixis. The spatiotemporal processes driving Sorbus diversification remain poorly understood. This research aims to provide insights into the evolution and diversification patterns of mountain whitebeam (S. austriaca) covering most of its range in the mountains of Central and South-eastern Europe. Our molecular and morphometric data revealed pronounced cryptic diversity within the S. austriaca complex; it is composed of different lineages, that likely originated via multiple allopolyploidisations accompanied by apomixes, and these lineages exhibit different distribution patterns. Our results are particularly valuable from a biodiversity conservation perspective due to the continuing generation of novel diversity in sympatric populations of the parental taxa. Such derived diversity requires process-oriented conservation plans and measures. Abstract The interplay of polyploidisation, hybridization, and apomixis contributed to the exceptional diversity of Sorbus (Rosaceae), giving rise to a mosaic of genetic and morphological entities. The Sorbus austriaca species complex from the mountains of Central and South-eastern Europe represents an allopolyploid apomictic system of populations that originated following hybridisation between S. aria and S. aucuparia. However, the mode and frequency of such allopolyploidisations and the relationships among different, morphologically more or less similar populations that have often been described as different taxa remain largely unexplored. We used amplified fragment length polymorphism (AFLP) fingerprinting, plastid DNA sequencing, and analyses of nuclear microsatellites, along with multivariate morphometrics and ploidy data, to disentangle the relationships among populations within this intricate complex. Our results revealed a mosaic of genetic lineages—many of which have not been taxonomically recognised—that originated via multiple allopolyploidisations. The clonal structure within and among populations was then maintained via apomixis. Our results thus support previous findings that hybridisation, polyploidization, and apomixis are the main drivers of Sorbus diversification in Europe.

A study of the phytochemical and molecular characteristics of ten Micromeria and six Clinopodium taxa (family Lamiaceae) distributed in the Balkan Peninsula was carried out. The phytochemicals detected in essential oils by gas chromatography, mass spectrometry, and molecular data amplified fragment length polymorphism were used to study the taxonomic relationships among the taxa and the correlations between phytochemical and molecular data. STRUCTURE analysis revealed three genetic groups, while Bayesian Analysis of Population Structure grouped the studied taxa into 11 clusters nested in the groups obtained by STRUCTURE. Principal components analysis performed with the 21 most represented compounds in the essential oils yielded results that were partly consistent with those obtained by STRUCTURE and neighbour-joining analyses. However, their geographic distributions did not support the genetic grouping of the studied taxa and populations. The Mantel test showed a significant correlation between the phytochemical and genetic data (r = 0.421, p < 0.001). Genetic distance explained 17.8% of the phytochemical distance between populations. The current taxonomic position of several of the studied taxa is yet to be satisfactorily resolved, and further studies are needed. Such future research should include nuclear and plastid DNA sequences from a larger sample of populations and individuals.

Here, from macrophylogeographic mtDNA empirical data, we proposed a scenario of the evolution and speciation of two important forest trees, European Black Pine and Scotch Pine, and their multiple subspecies and varieties. Molecular clock simulations revealed that INDELs variability in the Pinus mitochondrial genome is relatively old, i.e., from the Pliocene-Miocene epoch, and related to historical tectonic continental fluctuations rather than climate change on a large geographic scale. Special attention is paid to the relationships between different speciation models and historical migration patterns and between peripheral and central populations. Species evolution involves the mixing of different speciation modes rather than only one of them, and one speciation mode has different results/effects on different DNA types (e.g., mitochondrial vs. chloroplast vs. nuclear DNA). The misbalance between different meta-population census size vs. effective population size contributions for asymmetric migration pattern is a result of different genotypes (and sub-phylogenetic lines) responding to selection pressing and adaptive evolution.

Abstract The name Thymushumifususvar.aureopunctatus, described from Bosnia and Herzegovina, is lectotypified, and its taxonomic value is discussed. Thymusrichardiisubsp.richardii is currently considered an endemic subspecies common to Mallorca (Balearic Islands) and Bosnia and Herzegovina from the Balkan Peninsula. Specimens identified as Th.richardii from both Balearic Islands and Bosnia and Herzegovina were studied to determine if they are indeed the same taxonomic entity. Detailed micromorphological observations and morphometric analysis, suggest that the Balkan plants (Th.humifususvar.aureopunctatus) and the Majorcan populations (Th.richardiisubsp.richardii) are clearly separate entities. For the former name, based on morphological, phytochemical, biogeographical and present results, we propose the subspecific rank, as Th.richardiisubsp.aureopunctatuscomb. & stat. nov. Full descriptions of all five subspecies currently accepted within Th.richardii are provided.

Cotoneaster integerrimus represents a multiploid and facultative apomictic system of widely distributed mountain populations. We used flow cytometry to determine genome size, ploidy level, and reproduction mode variation of the Balkan populations, supplemented by analysis of nuclear microsatellites in order to address: (i) geographic distribution and variation of cytotypes among the populations; (ii) variation of reproduction mode and the frequency of sexuality; (iii) pathways of endosperm formation among the sampled polyploids and their endosperm balance requirements; (iv) genotypic diversity and geographic distribution of clonal lineages of polyploids. The prevalence of apomictic tetraploid cytotype followed by sexual diploids and extremely rare triploids was demonstrated. This prevalence of tetraploids affected the populations’ structure composed from clonal genotypes with varying proportions. The co-occurrence of diploids and tetraploids generated higher cytotype, reproductive mode, and genotypic diversity, but mixed-ploidy sites were extremely rare. The endosperm imbalance facilitates the development and the occurrence of intermediate triploids in mixed-ploidy populations, but also different tetraploid lineages elsewhere with unbalanced endosperm. All these results showed that the South European populations of C. integerrimus have higher levels of cytotype and reproductive diversity compared to the Central European ones. Therefore, the South European populations can be considered as a potential reservoir of regional and global diversity for this species.

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.

Chemical profile and antioxidant activity of the species Veronica saturejoides Vis. ssp. saturejoides (Plantaginaceae)—which is endemic to Croatia, Bosnia and Herzegovina and Montenegro —were investigated. Volatile compounds produced by glandular trichomes (composed of one stalk cell and two elliptically formed head cells according to scanning electron microscope investigation) were isolated from the plants collected in two locations. Additionally, as a part of specialized metabolites, total polyphenols, total tannins, total flavonoids and total phenolic acids were determined spectrophotometrically. In the lipophilic volatile fractions-essential oils, the most abundant compounds identified were hexahydrofarnesyl acetone, caryophyllene oxide and hexadecanoic acid. In total, the class of oxygenated sesquiterpenes and the group of fatty aldehydes, acids and alcoholic compounds dominated in the essential oils. In the hydrophilic volatile fractions-hydrosols, the most abundant compounds identified were trans-p-mentha-1(7),8-dien-2-ol, allo-aromadendrene and (E)-caryophyllene. A group of oxygenated monoterpenes and the sesquiterpene hydrocarbons dominated in the hydrosols. Antioxidant activity of essential oils and hydrosols was tested with two methods: 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC). Essential oils showed higher antioxidant activity than hydrosols and showed similar antioxidant activity to Rosmarinus officinalis essential oil. Obtained results demonstrate that this genus is a potential source of volatiles with antioxidant activity.