Distribution of the endemic Balkan flora on serpentine I. – obligate serpentine endemics

Serpentine (ophiolithic) substrate covers large areas in the Balkans, more so than in any other part of Europe. These areas extend from north to south mainly in the mountainous central regions and represent specialized habitats for basiphilous-calcifugal plants. Biodiversity in the area is high, with a great number of interesting local and regional endemics. The high number of endemics indicates the importance of serpentine habitats as centres for floristic differentiation and speciation. The number of Balkan endemics growing on serpentine is c. 335 taxa (species and subspecies) of which 123 are obligate. Their distribution is presented in 50 × 50 km UTM squares as adopted in the Atlas Florae Europaeae project coordinated at Helsinki. The richest (in number of taxa) squares are situated in NW Greece (Epirus), the island of Evvia, N Albania together with SW Serbia, and N Greece (Vourinos). They indicate important centres of plant diversity in the Balkans, areas to be noted for conservation strategy. Features responsible for the distribution and abundance of these obligate serpentine endemics include: 1) edaphic isolation in relation to type of bedrock (lime, dolomite, marble, schist, etc.), 2) mountain island isolation (Smolikas, Vourinos, Ostrovica, etc.), 3) island isolation (Evvia) and 4) continuous long-term isolation without interruption or disturbance of speciation.     

Typology and ecology of Californian serpentine annual grasslands

Abstract. A first classification for serpentine annual grasslands distributed throughout northern and central California is proposed. This study has followed the Braun‐Blanquet phyto‐sociological system based on floristical, biogeographical and bioclimatic features of the sampled areas. Numerical analyses of classification and ordination were applied to the floristic relevés. Minimum Variance Clustering grouped relevés into basic classification units that allowed us to define low‐hierarchical syntaxonomical units (associations) and ‘communities’. A Principal Coordinate Analysis was used to extract those ecological parameters related to the axes that separate those classification units from the previous dendrogram. The results showed that differences in species composition was mainly due to a continentality gradient and the shady effect of an overstory vegetation. On the basis of both analyses we propose a first syntaxonomic scheme on ultramafic (mainly serpentine) annual plant communities of the biogeographical Californian Region that comprises four associations, two subassociations and some provisional communities.     

Assessing wildfire vulnerability of vegetated serpentine soils in the Balkan peninsula

The endemic vegetation on serpentine soils is remarkably diverse and usually of low productivity and recovers slowly after major disturbances like wildfires and subsequent runoff, erosion, and landslides. Climate change and anthropogenic factors may increase the vulnerability of these ecosystems to disturbances with social and ecological consequences. The assessment of wildfire risks of these habitats is crucial for a targeted management to protect ecological, agricultural, and urban systems. The major goal of this study is to highlight the importance and utility of wildfire risk assessment for sustainable management of serpentine soils and the related vegetation cover. In this paper we present an example from Albania where the coverage of serpentine soils (11.2%) is about four times higher than the global average (3%). We used the wildfire ignition probability index (WIPI) and wildfire spreading capacity index (WSCI) as wildfire risk indicators. WIPI values were more evenly distributed while higher WSCI values were mostly concentrated in remote, high-elevation areas. The inner areas within serpentine soils were at lower risk regarding wildfire ignition, while higher values were found at the borders of serpentine soils that are closer to urban and residential areas. The distribution of normalized wildfire risk indices by vegetation type showed that overall habitats covered by sclerophyllous vegetation had the highest risk for wildfire ignition, followed by forested areas, while moors and heathland had the lowest risk. On the other hand, the WSCI was higher for forested areas, especially broad-leaved, coniferous, and mixed forests. Higher WIPI and WSCI values were associated with municipalities with less resources to mitigate the consequences for wildlife and implement preventive measures. According to our study, considerable surfaces of vegetation covering the serpentine soils in Albania are exposed to significant wildfire ignition and spreading risks. We argue that these areas need to be considered for a special protection status. This would facilitate a proper management of this unique soil type and improve the conservation of these fragile ecosystems.     

The origin of the serpentine endemic Minuartia laricifolia subsp. ophiolitica by vicariance and competitive exclusion

Serpentine soils harbour a unique flora that is rich in endemics. We examined the evolution of serpentine endemism in Minuartia laricifolia, which has two ecologically distinct subspecies with disjunct distributions: subsp. laricifolia on siliceous rocks in the western Alps and eastern Pyrenees and subsp. ophiolitica on serpentine in the northern Apennines. We analysed AFLPs and chloroplast sequences from 30 populations to examine their relationships and how their current distributions and ecologies were influenced by Quaternary climatic changes. Minuartia laricifolia was divided into four groups with a BAPS cluster analysis of the AFLP data, one group consisted only of subsp. ophiolitica, while three groups were found within subsp. laricifolia: Maritime Alps, north‐western Alps and central Alps. The same groups were recovered in a neighbour‐joining tree, although subsp. ophiolitica was nested within the Maritime Alps group of subsp. laricifolia. Subspecies ophiolitica contained three different chloroplast haplotypes, which were also found in the Maritime Alps group of subsp. laricifolia. Given its high genetic diversity, subsp. ophiolitica appears to have arisen from subsp. laricifolia by vicariance instead of by long‐distance dispersal. Genetic and geographic evidence point to the Maritime Alps populations of subsp. laricifolia as the closest relatives of subsp. ophiolitica. We hypothesize that M. laricifolia was also able to grow on nonserpentine rocks in the northern Apennines during glacial periods when the vegetation was more open, but that only the serpentine‐adapted populations were able to persist until the present due to their competitive exclusion from more favourable habitats.     

Onosma bulgarica sp. nov. (Boraginaceae–Lithospermeae) found on serpentine in Bulgaria

A new species, Onosma bulgarica (Boraginaceae–Lithospermeae), found in the eastern Rhodope Mountains in Bulgaria is described. It is a typical serpentinitophyte with local distribution and is thus a further addition to the remarkable serpentine flora. The new species belongs to the asterotrichos Onosma species and shows similarities with other endemics distributed on the Balkan Peninsula. Onosma bulgarica is clearly morphologically delimited by its suffruticose dense caespitose habit, very narrow basal and cauline leaves, bracts of lower flowers shorter than calyx and pedicel, corolla pale yellow and glabrous and short anthers. The differences between the new species and related taxa are discussed.     

Palaeoecological interpretation of the late Miocene landscapes and vegetation of northern Greece: A comment to Merceron et al., 2016 (Geobios 49, 135–146)

Recent works on feeding habits of ungulates, isotopic composition of equid tooth enamel, and phytoliths from late Miocene localities of northern Greece suggested the presence of savannah and excluded dense forests. Furthermore, Mediterranean-like climates were advocated for the late Miocene of Greece. Here, I compare palaeoenvironments inferred for two mammal localities from Chalkidiki and the Axios Valley (Nikiti, upper Vallesian and lower Turolian; Dytiko, upper Turolian) with evidence from contemporaneous plant assemblages from adjacent areas in Greece and Bulgaria. I use vegetation units inferred from pollen and spore, fruit and seed, and leaf assemblages and compare them with the vegetation inferred from mammal and phytolith data. Open vegetation as inferred from mammal and phytolith data is also part of the range of vegetation units discovered from the pollen and spore, seed and fruit, and leaf record (here called the palaeobotanical record). Poaceae are consistently present in late Vallesian to late Turolian pollen records of northern Greece. Further, a number of vegetation units are indicative of forest vegetation ranging from lowland to upland forests dominated by woody angiosperms and mixed coniferous-angiosperm forests. The presence of such forests is not in conflict with the results from mammal and phytolith studies, but it broadens the view on landscapes present in the late Miocene of northern Greece. In addition to a generalized vegetation type commonly inferred by mammal studies, the palaeobotanical record demonstrates the presence of various complementary vegetation types. A comprehensive view on late Miocene landscapes in northern Greece shows that there is no conflict in inferring open herb dominated landscapes and light to dense forests and provides new opportunities for the ecological interpretation of late Miocene ungulates.     

The shaping of mitochondrial DNA phylogeographic patterns of the brown hare (Lepus europaeus) under the combined influence of Late Pleistocene climatic fluctuations and anthropogenic translocations

The phylogeographic structure of the brown hare (Lepus europaeus) was studied by analysing mtDNA control region sequences of 98 individuals from continental and insular Greece, Bulgaria, Cyprus and northern Israel, together with 44 published sequences from Italy and central Europe. We found two distinct clades separated by an average nucleotide divergence of 6.6%, which may correspond to a Balkan and to an Asia Minor refugium. The estimated time of separation of the two clades was dated back to 105,000- 490,000 years ago. These two clades coexist in the area of northeastern Greece and Bulgaria, most likely as a result of a post-glacial northward expansion. Within the southern Balkan refugium, network analyses showed geographical structuring, which supports the hypothesis of several isolated Late Pleistocene populations. The central European and Italian populations appear to have originated from a non-detected northern Balkan population that was genetically closely related to some northern Greek populations, as a result of postglacial expansion, translocations or a combination of both. Moreover, several cases of ancient and recent translocations by humans were detected, especially for some island populations, while the eastern Aegean islands off the Asia Minor coast were most likely colonized naturally through Late Pleistocene land bridge connection. The genetic analysis presented here provides a framework for designing proper conservation and management guidelines for this species.     

Taxonomy and ecology of <Emphasis Type="Italic">Castanea sativa</Emphasis> Mill. forests in Greece

Castanea sativa Mill. is an important species of the Balkan Peninsula with high ecological and economic value. This article contributes to a phytosociological synsystematic approach of the C. sativa plant communities in Greece that covers the southern part of the Balkan Peninsula and describes the ecological parameters involved in their distribution and taxonomy. Phytosociological data have been collected from 14 mountainous areas across continental Greece, which are considered representative of the main forest types of C. sativa in the area. The 14 mountains demonstrate a variety of environmental conditions. Five communities (associations) and seven sub-communities (sub-associations) have been identified and described using TWINSPAN, Corespondence Analysis and the Braun-Blanquet classification scheme. Castanea sativa (chestnut) forests of Greece can be distinguished as three broad groups, defined primarily by their geographical distribution. In northern and central Greece chestnut stands are characterized by their high floristic homogeneity, which is reflected in the identification of only one community per region. Chestnut forests in northern Greece, in particular, exhibit strong floristic similarities with those of the rest of the Balkans. In southern Greece, on the other hand, the southern distribution limit of chestnut in the Balkans, there is a greater floristic diversity between the sampled mountains which is reflected in the presence of three confirmed communities and two sub-associations. Several factors have been identified as important in determining the structure and floristic composition of chestnut forests in Greece. Whilst climate and the grazing regime are influential, the degree of silvicultural management appears to be the most important factor determining the floristic composition of chestnut forests and their long-term sustainability.     

The Balkan wet grassland vegetation: a prerequisite to better understanding of European habitat diversity

The knowledge of broad-scale floristic variation in wet grasslands, which are endangered throughout Europe, is still limited and some regions have remained unexplored so far. In addition, hitherto published phytosociological studies were concentrated at the national level and therefore national vegetation classifications are not consistent with each other. In order to overcome these shortcomings of traditional phytosociology, we gathered original data from Bulgaria and analysed them together with the data from Central Europe. We further analysed major compositional gradients within Bulgarian wet grasslands and changes in species richness along them. We sampled 164 wet grassland vegetation plots throughout Bulgaria. We further prepared a restricted data set of wet grasslands from Central-European phytosociological databases. Both data sets were merged and classified by modified TWINSPAN. Four distinct vegetation types were differentiated. Even if they correspond with traditional alliances, which are primarily drawn as geographically defined units in Western and Central Europe (sub-Mediterranean Trifolion resupinati, sub-continental Deschampsion cespitosae and Molinion caeruleae and sub-oceanic Calthion palustris), they all occur in Bulgaria. When more precise classification was applied, two types of sub-Mediterranean wet grasslands and one high-altitude type of Calthion grasslands were detected solely in Bulgaria. DCA analysis showed that altitude is a dominant gradient controlling variation in Balkan wet grasslands. The second DCA axis was interpreted as the gradient of nutrient availability. Species richness shows skewed-unimodal trends along both major gradients, with the highest species richness in intermittently wet nutrient-limited grasslands. Tukey post-hoc test of altitudinal differences amongst vegetation types is significant for all pairs of clusters, suggesting that altitudinal differentiation is responsible for co-occurrence of nearly all European types of wet grasslands in Bulgaria. Our results suggest that (1) climate is an important factor for the diversity of wet grasslands; (2) Balkan vegetation of middle altitudes matches with that of Central Europe, whereas that of the lowest altitudes corresponds rather to the sub-Mediterranean region and high mountains are specific; (3) upward shift of Central-European vegetation types in southern Europe, so often described in forest vegetation is also evident for grassland vegetation and (4) the high diversity of Balkan vegetation is determined by a diverse relief enabling confluence of habitats possessing different climatic conditions.     

Plant communities on serpentine in Scotland

The plant communities on serpentine are named, classified and briefly described. Vegetation specific for serpentine belongs to the Violetea calaminariae, the class of communities on heavy metal soils. Other individual associations occur on serpentine soils but these are part of more general classes. The relationship of the separate vegetation units with the soils and their range in climate are outlined.The nomenclature of the vascular plants is that of Clapham et al. (1962) of the mosses that of Warburg (1963) of the liverworts that of Paton (1965) and of the lichens that of James (1965).The author wishes to acknowledge his indebtedness to Mr J. S. Robertson for making the 1980 relevés of Unst and Fetlar available for this paper.     

The location of the<Emphasis Type="Italic">Mus musculus/M. domesticus</Emphasis> hybrid zone in the Balkans: clues from morphology

Three morphological characters were used to depict the position of the hybrid zone between two species of house mice,M. musculus Linnaeus, 1758 andM. domesticus Schwarz et Schwarz, 1943, across a vast area covering countries of the former Yugoslavia, Albania, Bulgaria and Greece. Quantitative approach based on a morphological index (MI), resembling the hybrid index widely used in allozyme-based genetic studies, was used. The zone crosses Slovenia south of the Sava River, and then follows the Dinaric Mts to Montenegro and northern Albania. Contrary to many previously published results, the zone was found to run parallel with northern borders of Albania and the former Yugoslavian Macedonia, about 150 km north of the Greek border, thus giving its course rather “shallow” appearance at this part of the Balkan Peninsula.     

The Balkan chamois,an archipelago or a peninsula? Insights from nuclear and mitochondrial DNA

The Balkan chamois (Rupicapra rupicapra balcanica) is widespread on the Balkan Peninsula, along mountain massifs from Croatia in the north to Greece in the south and Bulgaria in the east. Knowledge on the genetic structure of Balkan chamois populations is limited and restricted to local studies. Therefore, the main objective of this study was to use nuclear (16 microsatellites) and mitochondrial (partial 376 base pairs control region) markers to investigate the genetic structure of this chamois subspecies throughout its distribution range and to obtain information on the degree of connectivity of the different (sub)populations. We extracted DNA from bone, dried skin and muscle tissue and successfully genotyped 92 individuals of Balkan chamois and sequenced the partial control region in 44 individuals. The Bayesian analysis suggested 3 genetic clusters and assigned individuals from Serbia and Bulgaria to two separate clusters, while individuals from the other countries belonged to the same cluster. Thirty new haplotypes were obtained from partial mitochondrial DNA sequences, with private haplotypes in all analyzed populations and only two haplotypes shared among populations, indicating the possibility of past translocations. The subspecies genetic composition presented here provides the necessary starting point to assess the conservation status of the Balkan chamois and allows the development of conservation strategies necessary for its sustainable management and conservation.

     

Facilitation allows plant coexistence in Cuban serpentine soils

Serpentine soils represent stressful habitats where plants have to cope with heavy metals, moisture limitation and low nutrient availability. We propose that facilitation is an important mechanism structuring plant communities under such stressful conditions. Facilitation has been shown to generate the spatial association of species, forming discrete vegetation patches of phylogenetically distant species. We measured these spatial and phylogenetic signatures left by facilitation in a serpentine plant community of central Cuba. Our results show that seedlings preferentially grow under plants of different species, and that adults are significantly aggregated into vegetation patches. In these patches, adults tend to co‐occur with distant relatives, ultimately forming phylogenetically diverse neighbourhoods. We discuss possible mechanisms explaining how species adapted to serpentine areas may be acting as nurses, reducing the stressful conditions for the establishment of other species.     

Species adaptation in serpentine soils in Lesbos Island (Greece): metal hyperaccumulation and tolerance

Serpentine (ultramafic) soils, containing relatively high nickel and other metal concentrations, present a stressful environment for plant growth but also a preferred substrate for some plants which accumulate nickel in their tissues. In the present study we focused on: (1) the relationships between serpentine soils of Lesbos Island (Greece) and serpentinophilic species in order to test their adaptation to the ‘serpentine syndrome’, and (2) the Ni-hyperaccumulation capacity of Alyssum lesbiacum, a serpentine endemic, Ni-hyperaccumulating species, recorded over all its distribution for the first time. We sampled soil and the most abundant plant species from the four serpentine localities of Lesbos Island. Soil and leaf elemental concentrations were measured across all the sites. Our results confirmed our hypothesis that serpentinophilic species are adapted to elevated heavy metal soil concentrations but restricting heavy metal concentration in their leaves. We demonstrated that different A. lesbiacum populations from Lesbos Island present differences in Ni hyperaccumulation according to soil Ni availability. Our results highlighted the understanding of serpentine ecosystems through an extensive field study in an unexplored area. Alyssum lesbiacum and Thlaspi ochroleucum emerge as two strong Ni hyperaccumulators with the former having a high potential for phytoextraction purposes.     

Phytogeochemical,geographical and vulnerability study of the Paleosubtropical element <Emphasis Type="Italic">Notholaena marantae</Emphasis> subsp. <Emphasis Type="Italic">marantae</Emphasis> (Sinopteridaceae) at the western edge of its range

Serpentine outcrops are distinct from their background geological context, as they are often isolated from one another, and provide a home to a significant number of rare or endemic taxa. The aim of this study was to assess the Portuguese populations of one such taxon, Notholaena marantae subsp. marantae, including information on its biogeography, habitat, geographical range and conservation status. A detailed study was also made of the endemic association Notholaenetum marantae, a member of the Phagnalo saxatilis-Cheilanthion maderensis alliance, a type of vegetation included in the EU Habitats Directive 92/43/ECC. The distribution of Notholaena marantae was highly fragmented, with two sites accounting for over 50% of the total number of individuals recorded. The presence of N. marantae is associated with that of ultramafic rocks, which show specific geochemical features. The conservation status of the species is a cause for concern. We propose that the species be considered ‘vulnerable’ according to the criteria of the IUCN (2001), and that areas where its populations grow be protected. This study confirms the endemic status of N. marantae subsp. marantae in Portugal and the importance of the conservation of its serpentine habitats.     

Nutrient dynamics and carbon partitioning in larch seedlings (Larix kaempferi) regenerated on serpentine soil in northern Japan

Japanese larch (Larix kaempferi) grows at a relatively high rate in northern Japan, even in serpentine soil. Serpentine soil has high concentrations of heavy metals (Ni, Cr), excessive Mg, and is nutrient deficient. These factors often suppress plant growth. We examined the mechanisms of Japanese larch’s tolerance to serpentine soil. We compared growth, photosynthetic capacity, and concentrations of elements in needles and roots between larch seedlings growing in serpentine soil and in nonserpentine (i.e., brown forest) soil. Dry mass of needles, stems, and branches were lower in seedlings grown on serpentine soil than in those grown on brown forest soil. There were lower concentrations of phosphorus and potassium in seedlings grown on serpentine soil than in those grown on brown forest soil. Seedlings growing on serpentine soil had lower Ni in plant organs. Our results suggest that larch seedlings grown on serpentine soil were able to exclude toxic elements. Moreover, the photosynthetic capacity and nitrogen concentration in needles was almost the same for seedlings grown in the two soil types. A wide range in growth was observed among individuals grown on both soil types. This may be regulated by nitrogen storage in the roots.     

Biotechnological applications of serpentine soil bacteria for phytoremediation of trace metals

Serpentine or ultramafic soils are produced by weathering and pedogenesis of ultramafic rocks that are characterized by high levels of Ni, Cr, and sometimes Co, but contain low levels of essential nutrients such as N, P, K, and Ca. A number of plant species endemic to serpentine soils are capable of accumulating exceptionally high concentrations of Ni, Zn, and Co. These plants are known as metal “hyperaccumulators.” The function of hyperaccumulation depends not only on the plant, but also on the interaction of the plant roots with rhizosphere microbes and the concentrations of bioavailable metals in the soil. The rhizosphere provides a complex and dynamic microenvironment where microorganisms, in association with roots, form unique communities that have considerable potential for the detoxification of hazardous materials. The rhizosphere bacteria play a significant role on plant growth in serpentine soils by various mechanisms, namely, fixation of atmospheric nitrogen, utilization of 1-aminocyclopropane-1-carboxylic acid (ACC) as the sole N source, production of siderophores, or production of plant growth regulators (hormones). Further, many microorganisms in serpentine soil are able to solubilize “unavailable” forms of heavy metal–bearing minerals by excreting organic acids. In addition, the metal-resistant serpentine isolates increase the efficiency of phytoextraction directly by enhancing the metal accumulation in plant tissues and indirectly by promoting the shoot and root biomass of hyperaccumulators. Hence, isolation of the indigenous and stress-adapted beneficial bacteria serve as a potential biotechnological tool for inoculation of plants for the successful restoration of metal-contaminated ecosystems. In this study, we highlight the diversity and beneficial features of serpentine bacteria and discuss their potential in phytoremediation of serpentine and anthropogenically metal-contaminated soils.     

Relationships between serpentine soils and vegetation in a xeric inner-Alpine environment

Aims

In serpentinitic areas non-endemic plants suffer from the serpentine syndrome, due to high Ni and Mg concentrations, low nutrients and Ca/Mg ratio. We evaluated the environment-soil-vegetation relationships in a xeric inner-alpine area (NW Italy), where the inhibited pedogenesis should enhance parent material influences on vegetation.

Methods

Site conditions, topsoil properties, plant associations and species on and off serpentinite were statistically associated (51 sites).

Results

Serpentine soils had higher Mg and Ni concentrations, but did not differ from non-serpentine ones in nutrient contents. The 15 vegetation clusters often showed substrate specificity. Two components of the Canonical Analysis of Principal Coordinates, respectively related to Mg and to Ni and heat load, identified serpentine vegetation. Random Forests showed that several species were positively correlated with Ni and/or Ca/Mg or Mg, some were negatively associated with high Ni, Mg excess affected only few species. Considering only serpentine sites, nutrients and microclimate were most important.

Conclusions

Ni excess most often precludes the presence of plant species on serpentinite, while an exclusion due to Mg is rarer. Endemic species are mostly adapted to both factors. Nutrient scarcity was not specific of serpentine soils in the considered environment. Considering only serpentine sites, nutrient and microclimatic gradients drove vegetation variability.     

The resurrection flowering plant Ramonda nathaliae on serpentine soil – coping with extreme mineral element stress

Ramonda nathaliae (Gesneriaceae) is a rare desiccation tolerant flowering plant species of the Northern Hemisphere. This, mainly calcicole, preglacial relict species is endemic in the Balkan Peninsula, where it has survived in its refugial habitats of gorges and mountain slopes. At present, only two localities within its narrow range are known where it thrives in hostile serpentine habitats, and the adverse serpentine environment is bound to present further challenge to the adaptive capacity of R. nathaliae. In general, the occurrence of a resurrection flowering plant on serpentine soil is exceptional and the soil-plant relation of R. nathaliae in those circumstances is described here for the first time. The aim of this study was (i) to analyze mineral elements composition in soil from both serpentine and limestone habitats of the species and to compare the way peculiarities of the substrates are reflected in roots and leaves of plants from the respective soils; (ii) to evaluate the effect of heavy metal overload on the habit of serpentine R. nathaliae individuals. Serpentine soil, characterized by high levels of phytotoxic heavy metals (Ni, Cr, Co, Mn), hosts plants showing elevated metal contents in their organs. Ramonda plants from serpentine populations are able to maintain balance of Ca to Mg favourable to Ca (2.0 in roots, 2.7 in leaves) despite a strongly unfavourable Ca/Mg ratio in the soil (0.09). The greatest difference in concentrations was observed for the Ni content in plant tissues: serpentine plants had 57 and 20 times more Ni in their roots and leaves than the plants from limestone. Aluminium was present in similar concentrations in both soils, and was highly accumulated in plant tissues of the plants from both substrates. Metal-specific metabolic activity is demonstrated in bioaccumulation indices of several essential minerals (Ca, Mg, Cu, Zn). A significantly higher metal content found in roots in relation to leaves might indicate the plant's ability to immobilize the metals within the root tissues. Mycorrhizal fungi colonize plant roots from both substrates and apparently are important in improving the supply of nutrients, but they could also take part in toxic metal immobilization. The price of adaptation to the hostile environment is evident in the habit of R. nathaliae plants growing on serpentine: reduced size of rosettes and leaves, as well as chlorotic and necrotic leaf tips and margins.     

Karyotaxonomy of Greek serpentine angiosperms

The chromosome numbers are given for 20 angiosperm taxa, most of which grow predominately or exclusively on serpentine in Greece, and the karyotype morphology is illustrated in all cases but one. Chromosome data are provided for the first time for ten taxa ( Alyssum pogonocarpum, Centaurea charrellii, C. vlachorum, Cephalaria fanourii, Matricaria tempskyana, Onosma stridii, Scorzonera doriae, Silene fabarioides, S. salamandra, Trinia glauca ssp. pindica ) and for the endemic monospecific genus Leptoplax . A new number is reported for Thymus teucrioides ssp. candilicus . An unexpected dysploid number is recorded for a population of Leontodon hispidus ssp. hispidus. Chromosome number and karyotype details from Greek populations are presented for the rest of the taxa. Chromosomal evidence supports close relationships among members of Onosma subsect. Asterotricha . The unusual chromosome number of Centaurea vlachorum supports its placement either in C. sect. Jacea or C . sect. Cyanus . The evolution of taxa in sections Vierhapperia, Pulvinares , and Nervosae of Scorzonera appears to be connected with particular chromosomal rearrangements and dysploidy. Leptoplax does not share the same chromosome number with Peltaria but with Bornmuellera instead, something that facilitates infrageneric hybridization. Further issues of taxonomy, distribution, evolution and conservation of serpentine species are briefly discussed where appropriate. © 2002 The Linnean Society of London , Botanical Journal of the Linnean Society , 2002, 139 , 109–124.