Despite considerable progress, many details regarding the evolution of the Arcto-Tertiary flora, including the timing, direction, and relative importance of migration routes in the evolution of woody and herbaceous taxa of the Northern Hemisphere, remain poorly understood. Meehania (Lamiaceae) comprises seven species and five subspecies of annual or perennial herbs, and is one of the few Lamiaceae genera known to have an exclusively disjunct distribution between eastern Asia and eastern North America. We analyzed the phylogeny and biogeographical history of Meehania to explore how the Arcto-Tertiary biogeographic hypothesis and two possible migration routes explain the disjunct distribution of Northern Hemisphere herbaceous plants. Parsimony and Bayesian inference were used for phylogenetic analyses based on five plastid sequences (rbcL, rps16, rpl32-trnH, psbA-trnH, and trnL-F) and two nuclear (ITS and ETS) gene regions. Divergence times and biogeographic inferences were performed using Bayesian methods as implemented in BEAST and S-DIVA, respectively. Analyses including 11 of the 12 known Meehania taxa revealed incongruence between the chloroplast and nuclear trees, particularly in the positions of Glechoma and Meehania cordata, possibly indicating allopolyploidy with chloroplast capture in the late Miocene. Based on nrDNA, Meehania is monophyletic, and the North American species M. cordata is sister to a clade containing the eastern Asian species. The divergence time between the North American M. cordata and the eastern Asian species occurred about 9.81 Mya according to the Bayesian relaxed clock methods applied to the combined nuclear data. Biogeographic analyses suggest a primary role of the Arcto-Tertiary flora in the study taxa distribution, with a northeast Asian origin of Meehania. Our results suggest an Arcto-Tertiary origin of Meehania, with its present distribution most probably being a result of vicariance and southward migrations of populations during climatic oscillations in the middle Miocene with subsequent migration into eastern North America via the Bering land bridge in the late Miocene.

Cycas simplicipinna (T. Smitinand) K. Hill. (Cycadaceae) is an endangered species in China. There were seven populations and 118 individuals that we could collect were genotyped in this study. Here, we assessed the genetic diversity, genetic structure and demographic history of this species.

The mulberry genus, Morus L. (Moraceae), has long been taxonomically difficult, and its species circumscription has only been defined recently. This genus comprises ca. 16 species distributed across Asia and the Americas, yet its biogeographic history remains poorly understood. In this study, we reconstructed the phylogeny and explored the biogeographic history of Morus using a combination of newly generated and previously published Hyb-Seq data. Our nuclear phylogeny recovered three well-supported geographic clades of Morus and showed that M. notabilis (China) is sister to the American clade plus the Asian clade. Multiple reticulation events among species of Morus and extensive incomplete lineage sorting (ILS) likely explain the difficulties in inferring phylogenetic relationships within the genus. Divergence time estimation indicated that Morus originated at the Eocene–Oligocene boundary, and current lineages started to diverge during the early Miocene, there is ambiguity surrounding the ancestral area with the two most likely regions being Sino-Himalaya or the Americas. Biogeographic inference and the fossil record suggest that Morus might have experienced extensive local extinction events during the Tertiary. Morus has expanded its distributional range through two dispersals from the Sino-Himalayan and Sino-Japanese regions to Southeast Asia. In summary, our new phylogenetic scheme and the biogeographic history presented here provide an essential foundation for understanding species relationships and the evolutionary history of Morus.

Cinnamomum chago (family Lauraceae) is an essential source of timber and oil. This plant is narrowly distributed in the western part of the Yunnan Province. In this study, the distribution, habitat, and biological characteristics of C. chago were examined through field investigation. The genetic diversity and the variation of the remnant populations were also studied using the inter-simple sequence repeat technique. Results showed that C. chago is mainly distributed in the upstream tributary mountains of Lancang River in Yunlong County of Yunnan Province. The species distribution exhibited a fragmented pattern with five isolated populations and high-frequency anthropogenic interference. A combination of morphological features (opposite leaves, pinnate leaf veins, absence of glandular fossa, large drupe, small punch, and pollen surface with triangular spike grain, with cushion bumps at the base) indicated that C. chago is a key phylogenetic taxon between the two sections of Asian Cinnamomum plants (Sect. Camphora (Trew) Meissn. and Sect. Cinnamomum). Analysis of the genetic diversity of C. chago indicated that it has a moderately high level of genetic diversity at the population and species levels (populations level: N_e = 1.629, H = 0.348, I = 0.504, and PPB = 83.3%; species level: N_e = 1.864, H = 0.460, I = 0.652, and PPB = 100%). Analysis of molecular variance revealed that 17% of the genetic variation was divided between the populations, whereas 83% was observed within the populations. Based on these results, we suggest the inclusion of C. chago in the Wild Plants with Extremely Small Populations in China. Moreover, the species should be given special attention and protection. Some strategies were proposed for the conservation of the C. chago populations.

Impatiens wutaishanensis R.L. Liao & Lei Cai, a new species from Southeast Yunnan, China, is here described and illustrated. This new species is most similar to Impatiens parvisepala S.X. Yu & Y.T. Hou in its racemose inflorescences, its four lateral sepals, the leaf arrangement, and in having yellow flowers. However, it differs in the height of the plants, the length of the petiole, the size and shape of the leaf blade, the shape of the spur, and the number of flowers in each inflorescence. A detailed description, color photographs, and a provisional IUCN red list assessment are provided, and its geographical distribution, ecology, and morphological relationship with relevant similar species are discussed.