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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