The first record of a species belonging to the genus Chara L. subgenus Chara R.D.Wood section Grovesia R.D.Wood subsect. Willdenowia R.D.Wood from Europe is presented here, thus challenging the interpretation of its distribution pattern as an intertropical group of charophytes. The morphological characters of the specimens, as well as the results of a phylogenetic analysis, clearly identified them as Chara zeylanica J.G.Klein ex Willd. Although the subsection Willdenowia has yet to receive a thorough taxonomic treatment, a discussion of its relationship to other taxa of this subsection is provided despite the lack of a commonly agreed upon taxonomic concept. The ecological conditions of the Sardinian site of C. zeylanica are presented. Moreover, the status of and threats to this taxon, and hypotheses regarding potential pathways through which it reached Europe, are discussed.

The coastal waters are important transition zones for terrestrial nutrient and pollutant runoff and the open Sea. During the last decades, eutrophication has negatively influenced macrophyte communities of the coastal ecosystems, making restoration activities inevitable. This study analysed recent macrophyte vegetation and the reproductive potential through the sediment diaspore reservoir along the German Baltic Sea coastline. Salinity was identified to be the responsible factor for shifts in the macrophyte community with most commonly found species like Stuckenia pectinata or Myriophyllum spicatum. In contrast, the oospores of small charophytes (e.g. Tolypella nidifica) clearly dominated the sediment diaspore bank. The germination rates differed in the recent vegetation composition and the diaspore bank composition with Zannichellia palustris as the dominant species. However, several species not visually detected at the respective sites were represented in the diaspore bank and germinated at a low rate (e.g. Chara contraria and Lamprothamnium papulosum). The maximal germination frequency corresponded to the sediment layer in which diaspore density was the highest (5–15 cm). In conclusion, the germinable diaspores were observed at all sites. Considering the differences between the diaspore composition, recent vegetation and germination success, we have illustrated the potential of the diaspore banks for the restoration of the macrophyte communities after at least mid-term periods of disturbance.

The Baltic Sea, a young habitat in geological terms, is characterised by strong climatic and salinity gradients that determine species distribution and trigger adaptation processes. The aim here was to test the hypothesis that Baltic Sea charophytes which originate from large freshwater populations exhibit a higher genetic variability than euryhaline charophyte species, restricted to a small number of brackish-marine populations. For this, genetic variability of euryhaline, mesohaline and halotolerant freshwater charophytes with different distribution patterns and population sizes were analysed. Euryhaline Lamprothamnium papulosum, restricted to a few and small populations in the Baltic Sea, showed a complete lack of genetic variability. Also euryhaline Tolypella with large and widely distributed populations displayed only low genetic variability. On the other hand, mesohaline Chara canescens, one of the most common charophytes in the Baltic Sea, exhibited comparatively high genetic variability, in spite of its parthenogenetic mode of reproduction. Halotolerant Chara baltica, originating from freshwater ancestors with a huge number of populations all over Europe, showed a rather restricted genetic variability, indicating a habitat filter acting prior to colonisation of brackish habitats.

Chara canescens Loisel. is the only haplostichous charophyte species in Europe. Populations with parthenogenetically reproducing females have been described from several European locations. In contrast, populations with female and male individuals are known only from a few European sites. Male individuals of C. canescens were recently found in Sardinia (Italy) and studied by analysis of rbcL and matK gene sequences. Phylogenetic analysis demonstrated that all European samples of C. canescens formed a robust monophyletic group, in which the bisexual samples can be differentiated from parthenogenetic populations by rbcL and matK gene sequences. It was shown that the bisexual C. canescens, originated from Sardinia and Neusiedler See-Seewinkel (Austria), can be distinguished based on rbcL gene sequence data. Further vegetation surveys and a larger sample size will be needed to determine the degree of genetic diversity within and between the reproductive modes of C. canescens.

A Chara exhibiting extreme morphological features including stipulodes, spine cells, and bracteoles is described and subjected to barcoding procedures to determine whether it belongs to the Chara contraria group or the C. hispida group. MatK barcoding clearly placed it in the C. contraria clade which was consistent with gametangial morphology, but not stipulode, spine cell and bracteole morphology. The specimen was determined to be included in the Chara contraria var. hispidula taxon, not previously reported or described for Newfoundland, Canada, or the USA.