Aims: The tropical niche conservatism (TNC) hypothesis and the out of the tropics (OTT) hypothesis propose mechanisms generating patterns of species diversity across warm‐to‐cold thermal gradients at large spatial scales. These two hypotheses both integrate ecological and biogeography‐related evolutionary factors, but they predict opposite patterns for phylogenetic structure. Mount Namjagbarwa possesses one of the longest elevational gradients for flowering plant diversity in the world. We aim to analyse the elevational patterns of the phylogenetic structure of flowering plants in this mountain, and investigate underlying causes for the emergence of the patterns.Location: Mt. Namjagbarwa located at the eastern edge of the Himalaya.Methods: Species distribution data of Mt. Namjagbarwa were extracted from specimen records in online sources, literature, herbarium and our fieldwork. Bioclimatic data were extracted from the CHELSA database. Mt. Namjagbarwa was divided into 100‐m elevational belts, which were grouped into three elevation segments (100–2000 m, 2000–4000 m and 4000–5200 m) for data analysis. We calculated phylogenetic metrics for each belt. The relationships of phylogenetic metrics with elevation and climatic factors were analysed using generalized additive models and structural equation models.Results: A typical hump‐shaped pattern of species richness was observed along the elevational gradient of Mt. Namjagbarwa. However, the phylogenetic structure showed a zig‐zag pattern with the three elevation segments, each of which has different formation mechanisms. Temperature tolerance played important roles throughout the entire elevational gradient in species richness and phylogenetic structure.Main conclusions: Neither TNC nor OTT alone can fully explain the patterns of floristic assembly of the entire elevational gradient of Mt. Namjagbarwa. OTT and TNC are better explanation for the patterns of low and middle elevations respectively. Potential mechanisms for species assembly of different elevation segments in Mt. Namjagbarwa region alternate between niche convergence and niche conservatism. The patterns observed in this study are likely to be common across the entire Himalaya. This is important for preserving the evolutionary potential of mountain biodiversity. However, more studies are needed to determine the underlying mechanisms generating the zig‐zag pattern of the phylogenetic structure in the Himalaya.

A new species Sinosenecio yangii D.G. Zhang & Q. Zhou (Asteraceae, Senecioneae) from Guizhou Province, China, is described and illustrated based on its morphological characteristics and molecular evidence. It closely resembles S. confervifer and S. guangxiensis, the former in the scapigerous habit and smooth and glabrous achene surface, the latter in the calyculate involucre and purple abaxial leaf surface, and both in the shape and indumentum of leaf lamina, but differs markedly from the latter two in having fewer capitula and epappose achenes. Phylogenetic analysis based on nrITS and ndhC-trnV sequences shows that this new species belongs to the S. latouchei clade and is sister to S. guangxiensis with moderate support.

The evolution of spermatophytes (seed plants) is relatively well known in their evolutionary relationships over temporal changes, but their spatial evolution is another critical yet often neglected lens, especially using a taxon‐based approach. Here, by integrating geographic distributions and origin locations across 429 spermatophyte families worldwide with unsupervised machine learning approaches, we constructed a Spermatophyte Spatial Evolutionary System that classifies global spermatophytes into 18 distribution types and six distribution supertypes within three primary floristic elements: cosmopolitan, tropical, and temperate. We found that the three elements all primarily originated from Gondwana, with the cosmopolitan element being the youngest and the temperate element being the oldest in terms of origin. They primarily formed during the Tertiary, particularly between the Eocene and Miocene, driven mainly by climate, long‐distance dispersal, and tectonic movement, while each exhibited distinct migration routes and formation models. Our results provide novel insights into the spatial evolution of global spermatophytes and highlight that similar distribution patterns of spermatophytes were driven by their comparable formation processes and mechanisms at the levels of floristic element, distribution supertype, and type.

A new species Sinosenecio yangii D.G. Zhang & Q. Zhou (Asteraceae, Senecioneae) from Guizhou Province, China, is described and illustrated based on its morphological characteristics and molecular evidence. It closely resembles S. confervifer and S. guangxiensis, the former in the scapigerous habit and smooth and glabrous achene surface, the latter in the calyculate involucre and purple abaxial leaf surface, and both in the shape and indumentum of leaf lamina, but differs markedly from the latter two in having fewer capitula and epappose achenes. Phylogenetic analysis based on nrITS and ndhC-trnV sequences shows that this new species belongs to the S. latouchei clade and is sister to S. guangxiensis with moderate support.

Cornus sunhangii is a newly discovered species of Cornaceae and is endemic to Tibet, China. In this study, the complete chloroplast genome of C. sunhangii is described. The length of the chloroplast genome is 157,446 bp. The genome has quadripartite structure, which includes a large single-copy (LSC) region (86,861 bp), a small single-copy (SSC) region (18,331 bp), and a pair of inverted repeat (IR) regions (26,127 bp each). The complete chloroplast genome contains a total of 113 unique genes, of which 79 protein-coding genes, 30 tRNA genes, and 4 rRNA genes.