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Abstract Anaphalisis one of the largest genera of the Asian Gnaphalieae (Asteraceae) and is most diversified on the Qinghai-Tibet Plateau. The chromosome numbers and karyomorphology of six species from seven populations were investigated for the first time for this region. Chromosome numbers have been newly documented for four species: Anaphalis deserti(2n = 56 = 24 median [m]+ 24 submedian [sm]+ 8 acrocentric [st]); Anaphalis plicata(2n = 56 = 26m + 30sm); Anaphalis xylorhiza(2n = 28 = 2 median point [M]+ 14m + 12sm); and Anaphalis rhododactyla(2n = 56 = 32m + 24sm). Two further counts are in agreement with the previously reported numbers, that is, Anaphalis royleana(2n = 28 = 4M + 6m + 18sm) and Anaphalis margaritacea(2n = 28 = 12m + 16sm). A new polyploid cytotype (2n = 56 = 26m + 30sm) was found in the Zougong population of A. margaritacea. Polyploidy is for the first time reported for Anaphalis, with four out of seven counts being tetraploid. Our cytological results suggest that polyploids might have played an important role in the evolution of Anaphalison the Qinghai-Tibet Plateau.

Abstract Toxicodendronis a genus in the Rhuscomplex of Anacardiaceae with a disjunct distribution between eastern Asia and North America, extending to southeastern Asia and the neotropics. Nuclear (internal transcribed spacer, external transcribed spacer, and NIA-i3) and chloroplast (ndhFand trnL-F) sequences were used to construct phylogenetic relationships of Toxicodendron. Phylogenetic analysis of these data strongly support Toxicodendronas a monophyletic group distinct from other genera of the Rhuscomplex, and the phylogeny does not fully corroborate classification at the sectional level. Two temperate disjunct lineages were detected, one from section Toxicodendronand the other between the eastern North American Toxicodendron vernixand the eastern Asian Toxicodendron vernicifluum. Their divergence times were estimated to be 13.46 (7.95–19.42) and 7.53 (2.76–12.86) mya, respectively. The disjunction between section Griffithii(taxa from warm temperate to tropical Asia) and Toxicodendron striatum(from the neotropics) was supported and their divergence time was estimated to be 20.84 (11.16–30.52) mya in the early Miocene. Our biogeographic results and the paleontological data support the Bering land bridge as the most likely route to explain the temperate disjunctions, yet the tropical disjunction in Toxicodendronseems to be best explained by the North Atlantic land bridge hypothesis.

Abstract The Hengduan Mountains region of south-west China is a noted biodiversity hotspot, but the geographic origins and historical assembly of its rich endemic flora, including the sky-island species of Solms-laubachiaMuschl. (Brassicaceae), have been little studied. Previous molecular studies on the phylogeny of Solms-laubachiashowed it to be paraphyletic, leading to considerable expansion not only of its taxonomic limits, but also its geographic range, with the inclusion of taxa from outside the Hengduan region. However, these studies provided little resolution of interspecific relationships, preventing inferences about historical biogeography within the clade. In the present study, new sequence data from two nuclear genes (LEAFYand G3pdh) and two chloroplast intergenic spacers (petN–psbM and psbM–trnD) were combined with existing markers to increase phylogenetic signals. Phaeonychium villosum(Maxim.) Al-Shehbaz was found to be nested within Solms-laubachias.l. In general, phylogenetic relationships appear to be a good predictor of geography, with the Hengduan Mountain endemics embedded in a paraphyletic grade of species from the western Himalayas and central Asia, but they also imply morphological homoplasy. Incongruence was detected between the nuclear and chloroplast gene trees, perhaps resulting from incomplete lineage sorting of ancestral polymorphisms. The crown age of Solms-laubachias.l. was estimated to be approximately 1.42–3.68 mya, using Bayesian relaxed molecular clock analysis. Historical biogeographic analysis using a parametric dispersal–extinction–cladogenesis model inferred central Asia and the western Himalayas as most probable ancestral range of Solms-laubachias.l., and estimated higher rates of eastward expansion than westward during the diversification of descendant lineages. In summary, our results suggest that Solms-laubachias.l. originated during the Pliocene in central Asia, and subsequently migrated eastward into the Hengduan Mountains, colonizing sky-island, alpine scree-slope habitats that may have provided novel ecological opportunity and accelerated speciation, ultimately establishing this region as the present center of diversity of the genus.

Abstract Cytological characters of four species in Syncalathium(Asteraceae: Lactuceae), a small genus with six identified species endemic to alpine scree of the Sino-Himalayan region, are surveyed in this report. Three species (Syncalathium pilosum, Syncalathium chrysocephalum, and Syncalathium disciforme) are examined for the first time. Combined with our previous counts, five species have been cytologically investigated from the genus and the results indicated that all species are diploid with the basic somatic chromosome number of x=8. The karyotype asymmetry of Syncalathium soulieiis 2A, distinct from the other four species of 1A, and the remaining species are divided into two subgroups with different karyotypes, consistent with their morphological features. The significance of the cytological evolution of Syncalathiumis briefly discussed.