Coelogyne fimbriata and Steveniella satyrioides are now the only orchid species known to have food-deceptive flowers that are pollinated exclusively by eusocial, worker wasps. In C. fimbriata, floral odour appears to be the major attractant. Sub-populations may go through flowering seasons when pollinators are abundant or infrequent, but fruit set always remains low because the obligate pollinator does not often appear to transfer pollinaria between intercompatible genets.

Dendrobium is a large genus of tropical epiphytic orchids. Some members of this genus are in danger of extinction across China. To investigate orchid mycorrhizal associations of the genus Dendrobium, plants from two Dendrobium species (Dendrobium officinale and Dendrobium fimbriatum) were collected from two habitats in Guangxi Province, China, and clone libraries were constructed to identify the mycorrhizal fungi of individual plants. A low and high degree of specificity was observed in D. officinale and D. fimbriatum, respectively. Phylogenetic analysis revealed that the majority of Dendrobium mycorrhizal fungi are members of the Tulasnellaceae, but, in some plants, members of the Ceratobasidiaceae and Pluteaceae were also found. In D. officinale, individual plants associated with more than three fungi simultaneously, and, in some cases, associations with five fungi at the same time. One fungus was shared by individual plants of D. officinale collected from the two habitats. In D. fimbriatum, only one fungal partner was found in each population, and this fungus differed between populations. The two species of Dendrobium sampled from the same habitat did not share any fungal taxa. These results provide valuable information for conservation of these orchid species.

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Aphyllorchis yachangensis, a new holomycotrophic orchid from Guangxi, southern China is described and illustrated here. This new species is similar to A. caudata but differs from the latter mainly by the sepals acute at the apex, the hypochile with 2 smaller and semicircular wings, the epichile adaxially smooth, acute, the lateral lobes triangular-ovate and the column clavate.

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In order to explore the genetic diversity of the extremely small population wild plant Habenaria dentata and protect and optimize its wild resources. The genetic diversity of 133 samples from 6 wild populations of H.dentata was analyzed by ISSR molecular marker technique to provide a scientific basis for the screening of improved germplasm resources. The results show that the average number of alleles (Na) was 1.765, the average number of effective alleles (Ne) was 1.424, the average Nei 's gene diversity index (He) was 0.252, the average Shannon information diversity index (I) was 0.381, and the average percentage of polymorphic loci (PPL) was 76.499%. The variation within populations was 77.34%, and the variation between populations was 22.66%. Gene flow (Nm) was 1.705 8, greater than 1. The results of cluster analysis showed that the six populations were mainly divided into four branches and not classified according to geographical location. There was no significant correlation between geographical location and genetic distance between populations (r=0.557, P>0.05). The genetic diversity of H.dentata is high. Among the six wild populations, the genetic diversity of Mulun population is the highest and this population can be used as a key protection unit.

Background Understanding genetic diversity is a core issue in conservation genetics. However, previous genetic diversity evaluations of narrowly distributed species have rarely used closely related widespread species as a reference. Furthermore, identifying natural hybridization signals between narrowly and widely distributed sympatric species is of great importance for the development of species conservation programs. Methods In this study, population genotyping by sequencing (GBS) was performed for a narrowly distributed species, Geodorum eulophioides (endemic and endangered in Southwest China), and a widespread species, G. densiflorum. A total of 18,490 high-quality single nucleotide polymorphisms (SNPs) were identified at the whole-genome level. Results The results showed that the nucleotide diversity and heterozygosity of G. eulophioides were significantly higher than those of G. densiflorum, confirming that narrowly distributed species can still preserve high genetic diversity. Consistent with taxonomic boundaries, all sampled individuals from the two species were divided into two genetic clusters and showed high genetic differentiation between species. However, in a sympatric population, a few G. eulophioides individuals were detected with genetic components from G. densiflorum, suggesting potential interspecific natural hybridization. This hypothesis was supported by Treemix analysis and hand-hybridization trials. Invasion of the habitat of G. eulophioides invasion by G. densiflorum under anthropogenic disturbance may be the main factor causing interspecific hybridization. Conclusions Therefore, reducing or avoiding habitat disturbance is a key measure to protect the G. eulophioides populations. This study provides valuable information for future conservation programs for narrowly distributed species.