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Saxifraga, the most species-rich and taxonomically complex genus of Saxifragaceae, is a characteristic component of temperate to polar climatic zones and of montane to alpine vegetation belts in mountain ranges of the Northern Hemisphere. The genus encompasses more than 440 species, which display notable diversity in growth form, vegetative and reproductive characters, as well as in micromorphology of pollen grains and seeds. Using a large taxon set including representatives attributed to nearly all recognised subgenera, sections and subsections of Saxifraga(altogether 254 species), as well as a broad coverage of outgroup taxa, we inferred evolutionary relationships within Saxifraga, explored the reasons of the striking inconsistencies between previous taxonomic treatments of Saxifraga, estimated the degree of homoplasy in characters frequently employed for classification, assessed the role of hybridisation in the evolution of the genus and, finally, provided a phylogeny-based framework upon which to revise its taxonomy. The phylogenetic trees based on nuclear ribosomal internal transcribed spacer (ITS) and plastid trnL-trnFDNA markers, including more than 460 newly generated sequences, were generally highly congruent, except within a single clade (sect. Saxifraga), in which incomplete lineage sorting and presumably allopolyploid speciation plays an important evolutionary role. Major lineages of Saxifragaare concordantly resolved by the DNA markers from both organelles with mostly strong node support. Our molecular phylogenetic results support the recognition of at least 13 sections and 9 subsections within Saxifraga. A part of these lineages agrees well with previously recognised infrageneric groupings, whereas others are differently delineated. Some of the groups identified by molecular phylogenetics are characterised only by the combination of different morphological characters. Frequently, micromorphological characters support the clades in the phylogenetic tree comparatively well. We here provide new ranks for three infrageneric epithets, namely for sect. Saxifragasubsect. Androsaceaeand subsect. Arachnoideaeand sect. Porphyrionsubsect. Squarrosae. Finally, our study identifies remaining taxonomic uncertainties within Saxifraga.

The present study provides an updated inventory and classification of the plant communities of the Gobi region in southern Mongolia based on a set of 1418 sample plots. The vast Gobi landscape is characterised by a dry climate with mean annual precipitation in the semi-deserts of between 50 and 150 mm, while the highest mountain peaks may receive up to 200 mm/a. The wetter montane regions are composed of extrazonal communities including woodlands and comparatively dense mountain steppes. The surrounding lowlands are characterised by sparse and more diffuse vegetation comprising dry grass steppes and, more commonly, shrub formations. Water surplus sites host various salt-adapted vegetation types which contrast sharply with the surrounding semi-deserts in terms of their high vegetation cover and species richness. In total, 28 associations / communities plus 18 sub-associations / sub-communities or variants are listed. Nine of these are newly described, and the syntaxonomical status of several other units known from literature has been clarified. The distribution of the plant communities is exemplified by six vegetation profiles.

Along with four vegetation profiles taken in 1984 in S Tibet climatically induced regressive plant successions were observed. Recently, frost heaving-adapted plant communities of the free gelifluction belt have been descending toward the alpine belt. The hypso-zonal cyperaceae turfs of the alpine belt have been exfoliated by the Himalaya föhn, and the alpine steppe communities have been advancing for an unknown period of time. The following hypothesis for this is given: The turfs must be interpreted as relics formed under wetter climatic conditions before the start of the Himalaya föhn and the related Indian summer monsoon. It is concluded that this Kobresia pygmaea age occurred just after the deglaciation of the Tibetan plateau and before the start of the Indian summer monsoon.

The vegetation of Mt Everest is described by means of the dominant plant formations and characteristic features of biotopes. Climatic data givenin connection with weather observations show evidence that the extreme asymmetry of the altitudinal vegetation belt on the south and north slope is induced by heavy rainfall on the south slope and the desiccating effect of the Himalaya föhn in the valleys of the north slope. Biotope shift from hypsozonal distribution on the south slope to extrazonal distribution on the north slope is described, the patterns of the actual timber line are discussed in order to reconstruct the natural upper forest limit, and regressive plant successions during the last 400 years of man's impact are summarized. The dominant vegetation pattern of the alpine belt is compared with that in the European Alps. On the arid north slope alpine steppe communities occur up to 5 500 m. The highest altitudinal vegetation belt and the highest plant communities at 5 960 m are dominated by periglacial processes. The highest records of flowering plants (6 100/6 200 m) and lichens (7 400 m) are discussed in light of the present knowledge on high-altitude vegetation ecology.

Features the Primula rebeccae grown in limited areas in Bhutan. Inclusion of the P. rebeccae in the high-alpine species; Physical description of the plant; Basis for the name given to the plant.