Camellia flavida is an endangered species of yellow camellia growing in limestone mountains in southwest China. The current classification of C. flavida into two varieties, var. flavida and var. patens, is controversial. We conducted a genetic analysis of C. flavida to determine its taxonomic structure. A total of 188 individual plants from 20 populations across the entire distribution range in southwest China were analyzed using two DNA fragments: a chloroplast DNA fragment from the small single copy region and a single-copy nuclear gene called phenylalanine ammonia-lyase (PAL). Sequences from both chloroplast and nuclear DNA were highly diverse; with high levels of genetic differentiation and restricted gene flow. This result can be attributed to the high habitat heterogeneity in limestone karst, which isolates C. flavida populations from each other. Our nuclear DNA results demonstrate that there are three differentiated groups within C. flavida: var. flavida 1, var. flavida 2, and var. patens. These genetic groupings are consistent with the morphological characteristics of the plants. We suggest that the samples included in this study constitute three taxa and the var. flavida 2 group is the genuine C. flavida. The three groups should be recognized as three management units for conservation concerns.

All yellow Camellia plants in China are threatened, but their classification is contentious. Here, we performed a phylogenetic reconstruction based on nuclear double‐digest restriction site‐associated DNA sequencing (ddRAD), transcriptomes, nuclear ribosomal internal transcribed spacer (nrITS), and the small single‐copy region of the chloroplast genome, in combination with morphological evidence to help resolve taxonomic ambiguity of those rare and threatened species. Conflicting relationships were derived from nuclear and chloroplast sequences. The strong hybridization/introgression signal detected suggests reticulate evolution mainly caused this discordance pattern. The nuclear‐ddRAD and RNA‐seq phylogenies fit better to the yellow camellias' morphology, providing a clear resolution for inferring their relationships in China. Based on present phylogenetic analyses and morphological characters, we propose these taxonomic suggestions: (i) Camellia petelotii and Camellia nitidissima are distinct species; (ii) Camellia ptilosperma, Camellia longruiensis, Camellia longgangensis, and C. longgangensis var. grandis are conspecific with Camellia flavida; (iii) Camellia multipetala and C. longgangensis var. patens are synonyms of Camellia quinqueloculosa, and C. quinqueloculosa should be recognized as an independent species; (iv) Camellia wumingensis should be formally recognized as an independent species; (v) Camellia longzhouensis is a synonym of Camellia chrysanthoides; (vi) Camellia xiashiensis and Camellia parvipetala should be treated as synonyms of Camellia micrantha; (vii) Camellia achrysantha is a good species; (viii) Camellia tunghinensis is an independent species; (ix) species status of Camellia huana is well‐supported; and (x) Camellia pingguoensis var. terminals should be correctly identified to species level as Camellia terminalis. These results provide the basis for the recognition 20 yellow Camellia species in China.

Camellia debaoensis R.C.Hu & Y.Q.Liufu, sp. nov. is described and illustrated as a new species from southwestern Guangxi, China. It is morphologically similar to Camellia pubipetala Y. Wan & S. Z. Huang, C. mingii S.X. Yang and C. tuyenquangensis D.V. Luong, N.N.H. Le & N. Tran, but it differs from these species in having glabrous young branches, glabrous petiole, glabrous sepals, glabrous petals, glabrous stamens and glabrous ovary, 10 petals, cylindrical ovary and style 3-lobed to 1/6 style length.

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Siraitia grosvenorii, an economically important plant species with high medicinal value, is endemic to subtropical China. To determine the population structure and origin of cultivated S. grosvenorii, we examined the variation in three chloroplast DNA regions (trnR-atpA, trnH-psbA, trnL-trnF) and two nuclear gene orthologs (CHS and EDL2) of S. grosvenorii in 130 individuals, selected from 13 wild populations across its natural distribution range, and 21 cultivated accessions using a phylogeographic approach. The results showed non-overlapping distribution of chlorotypes, three distinct chloroplast genetic groups restricted to different mountain ranges, and comparable nuclear diversity among the distinct geographical groups, suggesting the existence of at least three separate refugia. The current phylogeographic patterns of S. grosvenorii probably resulted from long-term survival in multiple refugia and limited expansion. Our results also demonstrated that wild populations in northeastern Guangxi share the same gene pool as cultivated S. grosvenorii accessions, suggesting that the current cultivars originated from wild populations distributed in northeastern Guangxi. The results of this study provide insight into improving the efficiency of S. grosvenorii breeding using a genetic approach, and outline measures for the conservation of its genetic resources.

Background Hybridization is generally considered an important creative evolutionary force, yet this evolutionary process is still poorly characterized in karst plants. In this study, we focus on natural hybridization in yellow Camellia species, a group of habitat specialists confined to karst/non-karst habitats in southwestern China. Results Based on population genome data obtain from double digest restriction-site associated DNA (ddRAD) sequencing, we found evidence for natural hybridization and introgression between C. micrantha and C. flavida, and specifically confirmed their hybrid population, C. “ptilosperma”. Ecophysiological results suggested that extreme hydraulic traits were fixed in C. “ptilosperma”, these being consistent with its distinct ecological niche, which lies outside its parental ranges. Conclusion The identified hybridization event is expected to have played a role in generating novel variation during, in which the hybrid population displays different phenological characteristics and novel ecophysiological traits associated with the colonization of a new niche in limestone karst.

Pyracantha is naturally distributed from East Asia to the southeastern Europe regions, and seven species, including five endemic species, were recorded in China. Taxonomic problems within the genus persist, in which the identity of Pyracantha crenulata complex is not clear when referring to the existing species dichotomous key. P. crenulata complex contains three species: P. loureiroi, P. crenulata and P. fortuneana. Such incident might be due to the lack of proper analysis and evaluation of the characters at the population level when first described. To solve this problem, we sampled 48 populations of P. crenulata, examined 278 sheets of herbarium specimens, and conducted principal coordinate analysis (PCoA) on the morphological variations across different populations. Our findings indicated that P. crenulata complex does not display distinct, separated groups based on the morphological characteristics described in the existing species description, the shape of leaf, leaf margin, leaf apices and widest position of leaf are not distinct features for species delimitation in P. crenulata complex. As a result, we proposed that the P. crenulata complex should be recognized as a single species named P. crenulata.