Scots pine (Pinus sylvestris L.) and the taxa from the P. mugo complex can hybridize in the contact zones and produce fertile hybrids. A unique example of an early Holocene relict population of P. sylvestris and P. uliginosa (a taxon from the P. mugo complex) growing on the tops of Jurassic sandstone rocks is located in Błędne Skały (Sudetes). Phenotypically, there are trees resembling P. sylvestris, P. uliginosa and intermediate forms between them. We expected that some of P. sylvestris and/or P. uliginosa-like trees could be in fact cryptic hybrids resembling one of the parental phenotypes. To address this question, we examined randomly sampled individuals, using a set of plastid (cpDNA), nuclear (nDNA) and mitochondrial (mtDNA) markers as well as biometric characteristics of needles and cones. The results were compared to the same measurements of allopatric reference populations of the P. sylvestris and the P. mugo complex (Pinus mugo s.s, P. uncinata and P. uliginosa). We detected cpDNA barcodes of the P. mugo complex in most individuals with the P. sylvestris phenotype, while we did not detect cpDNA diagnostic of P. sylvestris within P. uliginosa-like trees. These results indicate the presence of cryptic hybrids of the P. sylvestris phenotype. We found only three typical P. sylvestris individuals that were clustered with the species reference populations based on needle and cone characteristics. Most trees showed intermediate characteristics between P. sylvestris and P. uliginosa-like trees, indicating intensive and probably long-lasting hybridization of the taxa at this area and subsequent gene erosion of parental species.

Leaves of 279 individuals of Salix reticulata, collected from eight populations in contemporary isolated parts of the species range in Europe, and for comparison, from one population in the Rocky Mountains, were measured and analysed statistically. The characters describing the leaf size were more variable than the shape characters. All size characters were statistically significantly correlated, as well as they positively correlated to the northern latitude and eastern longitude, and negatively related to the altitude. The shape describing characters were assumed to be independent of the environmental conditions. Relations between samples based on multivariate analyses showed that the biogeographical structure of the studied S. reticulata populations is not quite clear. The present results suggest early transatlantic migrations of the species, possibly at least two migration routes to Scandinavia, and close relations between the Tatra Mountains, the Alps and the Western Scandinavia.

In this study, 1159 seeds of 29 Central European species of the genus Veronica were analyzed based on scanning electron microscopy images. The species belonged to nine subgenera: Beccabunga, Chamaedrys, Cochlidiosperma, Pellidosperma, Pentasepalae, Pocilla, Pseudolysimachium, Stenocarpon and Veronica, following the newest phylogenetic classification of the genus. Nine measured characteristics of seeds and nine ratios were analyzed statistically using ANOVA followed by post hoc testing, cluster analysis and discriminant analysis. In most cases, the results were not congruent with the contemporary classification of the genus. Examinations of qualitative seed features by scanning electron microscopy included the cochlidiospermous or discoid seed type, the seed shape, the general sculpture of the seed coat surface, the sculpture of anticlinal and periclinal walls and some species-specific traits such as the presence of the epidermal appendix. All these features, apart from seed shape, were useful to distinguish all subgenera and some species within subgenera: Beccabunga, Chamaedrys, Pellidosperma, Pocilla (only V. filiformis) and Veronica. The identification key based on the seed micromorphological features was prepared.

Instytut Dendrologii PAN w Kórniku - Institute of Dendrology PAS (Kórnik, Poland)

In Europe, Juniperus sabina L. is a mountainous, rare species that creates small, scattered populations, suggesting their refugial nature. Recently, a new variety of this juniper, J. sabina var. balkanensis R. P. Adams et A. N. Tashev was described based on genetic studies. We expected morphological differentiation among isolated parts of the species range and between varieties, as was the case with other Mediterranean junipers. Cones, seeds and fragments of shoots from a total of 506 individuals were collected from 24 populations in Europe and for comparisons from three populations from Tian Shan. Almost all of the 16 analysed features significantly differentiated among populations and geographical regions as well as between the varieties, although most groups differed from others only in terms of a single feature. The thickness of cones, the width of shoots and the length of seeds were the most important features for differentiation. The geographical structure of the variation of J. sabina was weak, and comparative populations from Tian Shan were clustered with European populations, similar to the findings of a previous study on essential oils. We found slightly different patterns of variation of the two varieties of the species. The little intra-species differentiation could be the result of the long period of contact between nowadays distinct populations and their relatively late separation in the early Holocene.