Anthemissect.Hiorthia (Asteraceae) on Kriti Island, Greece: high ploidy levels and a new species.

A morphological and karyological investigation of the Anthemissect.Hiorthia representatives of Kriti (Greece) revealed that three different species are found on the island, all endemic, and each characterised by a different ploidy level based on the haploid series of x = 9. Anthemisabrotanifolia, the species with the widest distribution, is tetraploid with 2n = 4x = 36. A.samariensis, a local endemic of the Lefka Ori, was found being decaploid, with 2n = 10x = 90, the highest number ever recorded in Anthemis. The recently discovered population on Mt. Kedros (south-central Kriti) is morphologically distinct from all the Anthemis entities growing on Kriti; it also differs from the variable and widespread A.cretica group. It is here described as a new species, A.pasiphaes Goula & Constantinidis. It is a hexaploid, with 2n = 6x = 54. All chromosome numbers are reported for the first time. Polyploidy might have acted as a reproductive barrier among these perennial species, complementing isolation by spatial distance and evolutionary divergence. Further, it might have contributed adaptation advantages to these three predominately mountain species.

Stomata in Close Contact: The Case of Pancratium maritimum L. (Amaryllidaceae).

A special feature found in Amaryllidaceae is that some guard cells of the neighboring stomata form a "connection strand" between their dorsal cell walls. In the present work, this strand was studied in terms of both its composition and its effect on the morphology and function of the stomata in Pancratium maritimum L. leaves. The structure of stomata and their connection strand were studied by light and transmission electron microscopy. FM 4-64 and aniline blue staining and application of tannic acid were performed to detect cell membranes, callose, and pectins, respectively. A plasmolysis experiment was also performed. The composition of the connection strand was analyzed by fluorescence microscopy after immunostaining with several cell-wall-related antibodies, while pectinase treatment was applied to confirm the presence of pectins in the connection strand. To examine the effect of this connection on stomatal function, several morphological characteristics (width, length, size, pore aperture, stomatal distance, and cell size of the intermediate pavement cell) were studied. It is suggested that the connecting strand consists of cell wall material laid through the middle of the intermediate pavement cell adjoining the two stomata. These cell wall strands are mainly comprised of pectins, and crystalline cellulose and extensins were also present. Connected stomata do not open like the single stomata do, indicating that the connection strand could also affect stomatal function. This trait is common to other Amaryllidaceae representatives.

A Morphometric and Karyological Study of the Anthemis macedonica Group (Asteraceae, Anthemideae) Reveals a New Species from Greece.

A recent study of the Anthemis collections in the Balkans indicated that the taxa of the Anthemis macedonica group (A. macedonica subsp. macedonica, A. macedonica subsp. thracica, A. meteorica, A. orbelica) exhibit noteworthy morphological patterns not evaluated before. We applied morphometric approaches (principal components analysis, PCA; factor analysis on mixed data, FAMD) by considering 19 qualitative and 20 quantitative morphological characters, together with three ratios, in 26 populations of this group. Furthermore, the chromosome numbers and karyotype morphology were investigated in eight populations of the group, covering the taxa participating in the study. Our results revealed that the southernmost populations of the group represent a hitherto unknown species confined to serpentine: it is described here as Anthemis serpentinica Goula & Constantinidis. The morphological evidence supports the proximity of A. macedonica and A. orbelica, which would be better considered as subspecific entities of the same species. On the contrary, A. meteorica and A. thracica are retained as independent entities at species level. All taxa share the same diploid chromosome number of 2n = 2x = 18 with similar but not identical karyotypes. A brief description of all taxa, based on recent new collections, and a dichotomous key are presented. Lectotypes are designated for Anthemis macedonica and A. meteorica.

Plant Diversity of Mts. Oligirtos and Farmakas (NE Peloponnisos, Greece) with Emphasis on Their Endemic Flora.

Greece is known to be a biodiversity hotspot. Though the plant diversity of Peloponnisos, the southernmost part of the Greek mainland, has been well-studied during the past 200 years, there are still gaps in our knowledge. To this end, the flora of the neighboring mountains Oligirtos and Farmakas was investigated, with a total of 740 and 762 taxa (species and subspecies) recorded, respectively, of which 635 and 756 for the first time. Ten species or subspecies were previously not known from Peloponnisos. Endemics correspond to 10.2% and 8.9% of the total flora and are predominately hemicryptophytes and entomogamous. Almost half of them produce capsules. The number of endemics per 2 × 2 km grid cell reveals that their highest number is found in areas of high elevation, and corresponds to habitats above the tree line, or to the limestone cliffs vegetation. No less than 62 endemic plant taxa of Mt. Oligirtos and 58 of Mt. Farmakas are threatened. A comparison of Mts. Oligirtos and Farmakas with five neighboring mountains shows that elevation correlates positively with the number of regional or bi-regional endemics but not with local or narrow endemics. The importance of mountainous regions for plant conservation is stressed.

Thirty-two new and noteworthy floristic records from north-eastern Greece.

Background: The vascular flora of Greece comprises no less than 6,705 vascular plant taxa (species and subspecies, including established aliens) in an area of 131,957 km2. The phytogeographic region of north-east Greece (NE), an area characterised by physiographic diversity, is the richest floristic region in Greece, yet it remains less-explored compared to other regions. New information: We present an annotated inventory of 32 vascular plant taxa collected predominantly from the East Macedonia and Thrace Regions (Makedonia and Thraki, NE Greece), following fieldwork that took place between 2013 and 2021. In our results, we identify seven new additions to the Greek flora (Aethionemasaxatilesubsp.rhodopaeum, Anthericumramosum, Asteramellus, Euphorbiacarniolica, Hesperismatronalissubsp.matronalis, Saponariastranjensis and Silenefetlerii) and 25 new records to the regional Greek flora consisting of mostly rare Balkan endemics of a restricted distribution and presumable conservation priorities. Taxonomic comments are added, where necessary. IUCN threat categories are assigned to certain taxa. Our investigation highlights the importance of the Balkan border areas as a source of new floristic elements for single countries and points to the importance of range-restricted taxa, in addition to single-country endemics, to address plants with a narrow distribution pattern.

What Socrates drank? Comparative chemical investigation of two Greek Conium taxa exhibiting diverse chemical profiles.

Conium divaricatum, even though exhibiting morphological differences in comparison to its congener of European origin Conium maculatum, is still considered a disputed taxon often referred to as a synonym of the latter. Herein, essential oils of various plant tissues from several populations of both taxa were comparatively investigated, showing distinct chemical profiles. In the case of C. divaricatum, the essential oils were dominated by hydrocarbon esters, among which the main constituents 4'-oxodecyl hexanoate, 4'-oxododecyl hexanoate and 4'-oxooctyl hexanoate were isolated and identified as undescribed natural products. In contrast, the essential oils of C. maculatum were dominated by hydrocarbon alkanes, alkenes and ketones, as well as the polyacetylene (Z)-falcarinol. Even though determination of the total alkaloids content and toxicity assessment against the crustacean Artemia salina did not reveal significant differences, the distinct chemical profiles and the morphological differences observed for both taxa, strongly support their distinction as separate species.

Mountains and refuges: Genetic structure and evolutionary history in closely related, endemic Centaurea in continental Greece.

Mountains of continental Greece are one of the main Mediterranean biodiversity hotspots, very rich in endemic species. The speciation in this area might have resulted from two main factors: a complex orography and its role as a refugium during past glaciations. We have investigated genetic diversity and population structure for a group of narrow endemics of Centaurea subsect. Phalolepis, with three main goals: to investigate population structure of these narrow endemics, to check whether patterns of genetic variation are in agreement with recognized species boundaries, and to get insights into the process of diversification within this group. Fifteen populations belonging to seven species were genotyped using cpDNA (rpl32-trnL region) sequences and nuclear microsatellites (eight loci). SSR were used to assess genetic variability, to analyse molecular variance, to identify genetic barriers, to estimate recent and historical gene flow, and to carry out a model-based Bayesian clustering. Analysis of cpDNA was used to construct a haplotype network. Despite being narrow endemics, all the studied species show moderate to high SSR genetic diversity. Genetic isolation of populations is very high, with no current gene flow among them. Patterns of genetic structure indicate that there are more genetic clusters than there are currently recognized taxa. Genetic data suggest that isolation in mountain ranges and subsequent allopatric speciation would be the main driver of diversification in the group; the refugial nature of the mountains of continental Greece has allowed the maintenance of high within-population genetic diversity.

Phylogeny of the Centaurea group (Centaurea, Compositae) - geography is a better predictor than morphology.

The Centaurea group is part of the Circum-Mediterranean Clade (CMC) of genus Centaurea subgenus Centaurea, a mainly Mediterranean plant group with more than 200 described species. The group is traditionally split on morphological basis into three sections: Centaurea, Phalolepis and Willkommia. This division, however, is doubtful, especially in light of molecular approaches. In this study we try to resolve this phylogenetic problem and to consolidate the circumscription and delimitation of the entire group against other closely related groups. We analyzed nuclear (internal transcribed spacer of the ribosomal genes) and chloroplast (rpl32-trnL intergenic spacer) DNA regions for most of the described species of the Centaurea group using phylogenetic and network approaches, and we checked the data for recombination. Phylogeny was used to reconstruct the evolution of the lacerate-membranaceous bract appendages using parsimony. The magnitude of incomplete lineage sorting was tested estimating the effective population sizes. Molecular dating was performed using a Bayesian approach, and the ancestral area reconstruction was conducted using the Dispersal-Extinction-Cladogenesis method. Monophyly of the Centaurea group is confirmed if a few species are removed. Our results do not support the traditional sectional division. There is a high incongruence between the two markers and between genetic data and morphology. However, there is a clear relation between geography and the structure of the molecular data. Diversification in the Centaurea group mainly took place during the Pliocene and Pleistocene. The ancestral area infered for the Circum-Mediterranean Clade of Centaurea is the Eastern Mediterranean, whereas for the Centaurea group it is most likely NW-Africa. The large incongruencies, which hamper phylogenetic reconstruction, are probably the result of introgression, even though the presence of incomplete lineage sorting as an additional factor cannot be ruled out. Convergent evolution of morphological traits may have led to incongruence between morphology-based, traditional systematics and molecular results. Our results also cast major doubts about current species delimitation.

Volatile compounds in Thymus sect. Teucrioides (Lamiaceae): intraspecific and interspecific diversity, chemotaxonomic significance and exploitation potential.

Thymus sect. Teucrioides comprises three species, namely, T. hartvigii, T. leucospermus, and T. teucrioides, distributed in Greece and Albania. The volatile constituents of all species of the section were obtained by hydrodistillation and investigated by GC-FID and GC/MS analyses. Twenty populations were sampled and a total of 103 compounds were identified, representing 98.0-99.9% of the oil compositions. The oils were mainly characterized by high contents of monoterpene hydrocarbons (42.7-92.4%), with the exception of three oils for which oxygenated monoterpenes were the dominating constituents, viz., that of T. hartvigii ssp. macrocalyx, with linalool as main compound (89.2±0.5%), and those of T. hartvigii ssp. hartvigii and of one population of T. teucrioides ssp. candilicus, containing thymol as major component (46.4±3.1 and 38.2±3.9%, resp.). The most common compound in the oils of the 20 populations of the section was p-cymene. Considerable variation was detected within and among populations, and seven chemotypes were distinguished, i.e., p-cymene, linalool, p-cymene/thymol, p-cymene/γ-terpinene, p-cymene/borneol, p-cymene/γ-terpinene/borneol, and p-cymene/linalool chemotypes. Different chemotypes may exist in the same population. Multivariate statistical analyses enabled the segregation of the oils within Thymus sect. Teucrioides into two groups, one consisting of the three subspecies of T. teucrioides and the second comprising the species T. hartvigii and T. leucospermus. A linalool-rich chemotype, unique within the section, distinguished the oil of T. hartvigii ssp. macrocalyx from all other oils. The high oil content of p-cymene and the preference for serpentine substrates render T. teucrioides species promising for future exploitation.