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This study employs three nuclear genes (PHYA, LFY, and GAI1) to reconstruct the phylogenetic and biogeographic history of Magnoliaceae. A total of 104 samples representing 86 taxa from all sections and most subsections were sequenced. Twelve major groups are well supported to be monophyletic within Magnoliaceae and these groups are largely consistent with the recent taxonomic revision at the sectional and subsectional levels. However, relationships at deeper nodes of the subfamily Magnolioideae remain not well resolved. A relaxed clock relying on uncorrelated rates suggests that the complicated divergent evolution of Magnolioideae began around the early Eocene (54.57 mya), concordant with paleoclimatic and fossil evidence. Intercontinental disjunctions of Magnoliaceae in the Northern Hemisphere appear to have originated during at least two geologic periods. Some occurred after the middle Miocene, represented by two well-recognized temperate lineages disjunct between eastern Asia and eastern North America. The others may have occurred no later than the Oligocene, with ancient separations between or within tropical and temperate lineages.

Rhododendron Linnaeus (1753: 392) is one of the largest genera in the family of Ericaceae, which is subject to much ongoing taxonomic debate. About 1,025 species are recognized; these are distributed from the northern temperate zone, throughout tropical Southeast Asia, to northeastern Australia (Chamberlain et al. 1996). In China, there are 571 species classified in 6 subgenera, of which 405 species are endemic (Fang et al. 2005). Apart from Xinjiang and Ningxia, Rhododendrons have been documented in all other provinces (Ma et al. 2014; Wu et al. 2005).

Rhododendron baihuaense sp. nov. is described as a new species endemic to Yunnan, China, that has, to date, only been found in Baihualing on the eastern side of the Gaoligong Mountains. Morphologically, R. baihuaense can be readily distinguished from R. hanceanum and R. genestierianum, by its absent scales on mature leaves, only 2–5 flowers per inflorescence, the funnel-shaped flower and white corolla, and its slender and erect style. A molecular analysis based on the four standard DNA barcodes (rbcL, matK, trnH-psbA and ITS) indicates that R. baihuaense is genetically distinct from R. hanceanum and R. genestierianum, and, together with the morphological differences, is described here as a new species.

Trigonobalanus doichangensis is a national rare and endangered fagaceous plant of China. It is currently restricted to five sites, four in Yunnan province in south-western China and one in northern Thailand. We investigated the genetic diversity of T. doichangensis to provide information for the effective preservation of the genetic diversity of the species. Randomly amplified polymorphic DNA (RAPD) markers were used to assess the genetic variation and structure in each of the five extant populations. Sixteen primers produced 157 fragments, of which 83 (53%) were polymorphic. The estimated species diversity of T. doichangensis, although lower than for most fagaceous species, was within the range of values that have been reported for the family. The presence of private and/or uncommon fragments in each population, the presence of unique phenotypes in all individuals sampled, and estimates of relatively high populational fixation and low gene flow indicated that the species diversity present was mostly distributed among the five isolated extant populations. Pairwise genetic distances between populations were not correlated with geographical distances as depicted by the resolution of one of the Chinese populations as most similar to the Thailand population. Conservation of this species should include preservation of each of the five distinct extant populations.

Background Natural hybridization in plants is universal and plays an important role in evolution. Based on morphology it has been presumed that hybridization occurred in the genus Buddleja, though genetic studies confirming this assumption have not been conducted to date. The two species B. crispa and B. officinalis overlap in their distributions over a wide range in South-West China, and we aimed to provide genetic evidence for ongoing hybridization in this study. Results We investigated the occurrence of hybrids between the two species at the southern-most edge of the distribution of B. crispa using five nuclear loci and pollination experiments. The genetic data suggest substantial differentiation between the two species as species-specific alleles are separated by at least 7–28 mutations. The natural hybrids found were nearly all F1s (21 of 23), but backcrosses were detected, and some individuals, morphologically indistinguishable from the parental species, showed introgression. Pollen viability test shows that the percentage of viable pollen grains was 50 ± 4 % for B. crispa, and 81 ± 2 % for B. officinalis. This difference is highly significant (t = 7.382, p