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Neottia bifidus, a new mycoheterotrophic orchid, found in Maolan National Nature Reserve in Guizhou Province, China, is described and illustrated here. The new species is close to N. nidus-avis, N. kiusiana and N. papilligera but differs in having a finely pubescent rachis with fewer flowers, a finely pubescent pedicel, and a fishtail-shaped lip that is deeply bilobed to the middle of the lip, with the lobes diverging at an acute angle (45°) to each other and mesochile with many papillae. Additionally, N. bifidus is well supported as a new species by molecular phylogenetic results based on ITS and chloroplast genome. The chloroplast genome of the novelty, which contains an LSC region of 33,819 bp, SSC region of 5,312 bp and IRs of 46,762 bp was assembled and annotated. A key to mycoheterotrophic Neottia species in China is also provided.

According to Articles 53.1 of the International Code of Nomenclature for Algae, Fungi, and Plants (Shenzhen Code), Neottia bifida M.N.Wang (as 'bifidus'; PhytoKeys 229: 222, 2023) is an illegitimate name, and hence a new name Neottia maolanensis M. N. Wang is proposed here.

Cymbidium, which includes approximately 80 species, is one of the most ornamental and cultivated orchid genera. However, a lack of markers and sparse sampling have posed great challenges to resolving the phylogenetic relationships within the genus. In the present study, we reconstructed the phylogenetic relationships by utilizing one nuclear DNA (nrITS) and seven plastid genes (rbcL, trnS, trnG, matK, trnL, psbA, and atpI) from 70 species (varieties) in Cymbidium. We also examined the occurrence of phylogenetic conflict between nuclear (nrITS) and plastid loci and investigated how phylogenetic conflict bears on taxonomic classification within the genus. We found that phylogenetic conflict and low support values may be explained by hybridization and a lack of informative characteristics. Our results do not support previous classification of the subgenera and sections within Cymbidium. Discordance between gene trees and network analysis indicate that reticulate evolution occurred in the genus Cymbidium. Overall, our study indicates that Cymbidium has undergone a complex evolution.

Dendrobium thyrsiflorum H. G. Reichenbach ex André is an endemic herb with ornamental and medicinal orchid value distributed in Southeast of Yunnan of China. Here, we report and characterize the complete chloroplast (cp) genome sequence of D. thyrsiflorum in order to provide genomic resources helpful for its identification, conservation and utilization. The complete cp genome of D. thyrsiflorum is 160,123 bp, including one large single-copy region (LSC, 88,001), one small single-copy region (SSC, 21,142), and two inverted repeat regions (IRs, 25,490). The cp genome contains 143 genes, consisting of 110 unique genes (80 protein-coding genes, 26 tRNAs, and 4 rRNAS). The phlyogenetic relationships show that D. thyrsiflorum is closely related to other species of Dendrobium.

Pholidota imbricata belongs to tribe Coelogninae in Orchidaceae distributed in Sichuan, Xizang, and Yunnan. Here, we report the first complete chloroplast (cp) genome and the cp genome features of P. imbricata. The complete cp genome sequence of P. imbricata is 159,292 bp in length and presented a typical quadripartite structure including one large single-copy region (LSC, 87,515 bp), one small single-copy region (SSC, 20,999 bp), and two inverted repeat regions (IRs, 25,389 bp each). The cp genome encoded 141 genes, of which 108 were unique genes (80 protein-coding genes, 24 tRNAs, and 4 rRNAs). The phylogenetic relationships show that P. imbricata is sister to the species of the genus Pleione in tribe Coelogninae.

Cymbidium erythraeum Lindl. is an endangered species of Orchidaceae and distributed in China and Bhutan, India, Myanmar, Nepal, and Vietnam. Here, we report the complete chloroplast (cp) genome sequence and the cp genome features of C. erythraeum. The complete chloroplast (cp) genome sequence of C. erythraeum is 156,327 bp in length and including one large single-copy region (LSC, 85,404 bp), one small single-copy region (SSC, 20,021 bp), and two inverted repeat regions (IRs, 25,426 bp). The cp genome encoded 136 genes, of which 107 were unique genes (80 protein-coding genes, 23 tRNAs, and four rRNAs). The phylogenetic relationships show that C. erythraeum is closely related to other species in the genus Cymbidium and is sister with C. tracyanum.

BACKGROUND: The Aerides-Vanda alliance is a complex group in the subtribe Aeridinae (subfamily Epidendroideae, Orchidaceae). Some phylogenetic systems of this alliance have been previously proposed based on molecular and morphological analyses. However, several taxonomic problems within this alliance as well as between it and its allies remain unsolved. METHODOLOGY/PRINCIPAL FINDINGS: We utilized ITS and five plastid DNA regions in this phylogenetic analysis. Consensus trees strongly indicate that the Aerides-Vanda alliance is monophyletic, and the 14 genera of this alliance can be grouped into the following clades with 14 subclades: 1. Aerides, comprising two subclades: Rhynchostylis and Aerides; 2. Ascocentropsis; 3. Papilionanthe; 4. Vanda, comprising five subclades: Neofinetia, Christensonia, Seidenfadenia, Ascocentrum, and Vanda-Trudelia, in which Vanda and Trudelia form a subclade; 5. Tsiorchis, comprising three subclades: Chenorchis, Tsiorchis, and two species of Ascocentrum; 6. Paraholcoglossum; and 7. Holcoglossum. Among the 14 genera, only Ascocentrum is triphyletic: two species of the Ascocentrum subclade, an independent subclade Ascocentrum subclade in the Tsiorchis clade; the Ascocentrum subclade in the Vanda clade; and one species in the Holcoglossum clade. The Vanda and Trudelia species belong to the same subclade. The molecular conclusion is consistent with their morphological characteristics. CONCLUSIONS: We elucidate the relationship among the 14 genera of the Aerides-Vanda alliance. Our phylogenetic results reveal that the Aerides-Vanda alliance is monophyletic, but it can be divided into 14 genera. The data prove that Ascocentrum is triphyletic. Plants with elongate-terete leaves and small flowers should be treated as a new genus, Pendulorchis. Saccolabium himalaicum (Ascocentrum himalaicum) should be transferred to Pendulorchis. Ascocentrum pumilum, endemic to Taiwan, should be transferred to Holcoglossum. A new combination, Holcoglossum pumilum, was also established. Trudelia should not be recognized as an independent genus. Two new species, Pendulorchis gaoligongensis and Holcoglossum singchianum, were described as well.

Outcrossing is known to carry genetic advantages in comparison with inbreeding. In many cases, flowering plants develop a self-incompatibility mechanism, along with a floral component adaptation mechanism, to avoid self-pollination and to promote outbreeding. Orchids commonly have a lip in their flower that functions as the a visiting plate for insect pollinators. Aside from the lip, however, many species (including Coelogyne rigida) have sheaths around the axis of inflorescence. The function of these sheaths remains unknown, and has long been a puzzle to researchers.We investigated the function of these sheaths in relation to the lip and the pollinators, as well as their role in the modes of pollination and reproduction of Coelogyne rigida in 30 flowering populations of orchids in the limestone area of Southeast Yunnan, China. We found that self-incompatible C. rigida developed specialized bird perches around the basal axis of inflorescence to attract sunbirds and to complement their behavioral tendency to change foraging locations frequently. This self-incompatibility mechanism operates separately from the floral component adaptation mechanism. This mechanism thus prevents bees from repeatedly visiting the floral lip of the same plant which, in turn, results in autogamy. In this way, instead of preventing autogamy, C. rigida responds to these negative effects through a highly efficient cross-pollination method that successfully transfers pollen to different plants.The proposed method ensures reproductive success, while offsetting the infertile self-pollination by insects, thereby reducing mating costs and addressing the lack of cross-pollination. The adaptation provides a novel and striking example of structural adaptation that promotes cross-pollination in angiosperms.

BACKGROUND: Holcoglossum is a small orchid genus of 12 species ranging from SW China to Thailand and NE India. Although molecular and morphological analyses have been performed to establish the phylogenetic relationships within this genus, the interspecific relations and its relations with allied genera, such as Rhynchostylis, Aerides and Vanda, remain unclear. METHODOLOGY/PRINCIPAL FINDINGS: In addition to morphological analysis, maximum parsimony, maximum likelihood, and Bayesian inference analyses were performed based on fragments of the nuclear ITS and chloroplast trnL-F and matK genes of 31 taxa (15 Holcoglossum, 14 Aeridinae, 2 outgroups) representing all major clades of the Holcoglossum alliance. The results suggest that Holcoglossum is triphyletic, comprising three clades: the Holcoglossum clade, its sister clade, and a distant clade more closely related to Rhynchostylis, Aerides, and Vanda than to the Holcoglossum clade. The Holcoglossum clade is further divided into three subclades; the genetic distances between these three subclades also support this delimitation. The molecular conclusion is consistent with their distinct morphological characters. CONCLUSIONS: We propose that the latter two clades comprise two new genera, Paraholcoglossum and Tsiorchis, and Holcoglossum clade divides into three sections. In addition, a new section, Holcoglossum sect. Nujiangensia, and a new species, Holcoglossum linearifolium, are proposed. Some new combinations are made, and a new scheme is provided for the classification of all species of Holcoglossum, Paraholcoglossum, and Tsiorchis.

A highly efficient flame-retardant melamine salt (DPPMA) was synthesized from diphenylphosphinic acid (DPPA) and melamine (MA). The chemical structure of DPPMA was characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis, and the thermal degradation behavior was investigated by thermogravimetric analysis (TGA). Subsequently, flexible polyurethane foams (FPUFs) were prepared with DPPMA. Limiting oxygen index (LOI) tests, vertical burning tests, and cone calorimetric tests were carried out to investigate the combustion of the materials. The results showed that the FPUF with only 5 php DPPMA passed the vertical burning test and had an increased LOI value of 22%. The corresponding flame-retardant mechanism was systematically investigated by FTIR spectroscopy, TGA, and energy-dispersive X-ray (EDX) spectrometry. The results revealed that DPPMA released NH3 and H2O to dilute the combustible gas and phosphorus-containing radicals during combustion, which consumed the active free radicals produced by the FPUF. [ABSTRACT FROM AUTHOR]

Pendulorchis gaoligongense G. Q. Zhang, K. Wei Liu & Z. J. Liu var. lushuiensis L. J. Chen, X. C. Shi & W. H. Rao (Orchidaceae, Vandeae) is described and illustrated as a new variety from Yunnan, China. It differs from the typical variety, P. gaoligongense, by having shorter leaves that are 30–40 cm, smaller flowers that are 4–5 mm diameter, and a reddish white perianth (vs. leaves 40–60 cm, flowers 8–9 mm diameter, and a purple-red perianth). [ABSTRACT FROM AUTHOR]