Diversity

Research

Jump to: Review

11 pages, 9770 KiB

Open AccessEditor’s ChoiceArticle

Differing Life-History Strategies of Two Mycoheterotrophic Orchid Species Associated with Leaf Litter- and Wood-Decaying Fungi

by Yuki Ogura-Tsujita, Kenshi Tetsuka, Shuichiro Tagane, Miho Kubota, Shuichiro Anan, Yumi Yamashita, Koichi Tone and Tomohisa Yukawa

Diversity 2021, 13(4), 161; https://doi.org/10.3390/d13040161 - 8 Apr 2021

Cited by 6 | Viewed by 3461

Abstract

Mycoheterotrophic orchids depend completely on mycorrhizal fungi for their supply of carbon. The life-history traits of mycoheterotrophic plants (MHPs) can differ according to the characteristics of the associated mycorrhizal fungi. We compared the life-history strategies of two mycoheterotrophic orchids associated with wood- and [...] Read more.

Mycoheterotrophic orchids depend completely on mycorrhizal fungi for their supply of carbon. The life-history traits of mycoheterotrophic plants (MHPs) can differ according to the characteristics of the associated mycorrhizal fungi. We compared the life-history strategies of two mycoheterotrophic orchids associated with wood- and leaf litter-decaying fungi over a maximum of six years of field monitoring. Seventy percent of the aboveground stems of Erythrorchis altissima, associated with wood-decaying fungi, disappeared from the host wood within two years after tagging, likely due to nutrient depletion. In contrast, Gastrodia confusa, associated with leaf litter-decaying fungi, occurred continuously (18 to 108 fruiting stalks) every year within a small-scale plot (12 × 45 m) for six years through seed and clonal propagation. Our results support the idea that mycoheterotrophic orchids associated with wood-decaying fungi disappear from their habitats due to nutrient depletion after their host wood has mostly decayed, while mycoheterotrophic orchids associated with leaf litter-decaying fungi can survive in small-scale habitats where substantial leaf fall regularly occurs to sustain the associated fungi. Our study provides basic information about a unique life-history strategy in MHPs associated with saprotrophic fungi and an understanding of the variation in life-history strategies among MHPs. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Graphical abstract

14 pages, 1857 KiB

Open AccessEditor’s ChoiceArticle

The Diverse Assemblage of Fungal Endophytes from Orchids in Madagascar Linked to Abiotic Factors and Seasonality

by Kazutomo Yokoya, Lawrence W. Zettler, Jake Bell, Jonathan P. Kendon, Alison S. Jacob, Emily Schofield, Landy Rajaovelona and Viswambharan Sarasan

Diversity 2021, 13(2), 96; https://doi.org/10.3390/d13020096 - 23 Feb 2021

Cited by 7 | Viewed by 4181

Abstract

The inselbergs of the Central Highlands of Madagascar are one of many ‘micro-hotspots’ of biodiversity on the island, particularly for Orchidaceae. In this region are several genera that have a large number of endemic species that are in serious decline or edging towards [...] Read more.

The inselbergs of the Central Highlands of Madagascar are one of many ‘micro-hotspots’ of biodiversity on the island, particularly for Orchidaceae. In this region are several genera that have a large number of endemic species that are in serious decline or edging towards extinction. Studies relating to diversity of orchids and their fungal partners (both mycorrhizal and non-mycorrhizal root associates) deserve more attention, as climate change and human induced decline in resilience of species in the wild is at an all-time high. Identification of mycorrhizal fungi (MF) via conventional seed baited-protocorms has limitations for large scale studies and its application for time-bound conservation projects. The paper describes the value of understanding fungal diversity in the roots of orchids at different stages of maturity. The first part of the study was a preliminary investigation mainly to identify culturable Rhizoctonia endophytes, and the second part looked at all life forms of available taxa together with associated soil characteristics. We isolated and identified 19 putative MF from 18 of the 50 taxa spread over an area of 250 sq. km, covering three life forms, growth phases of the orchid taxa, and habitat types. In the rest of the taxa, we were unable to detect any putative MF, but had varying numbers of non-mycorrhizal endophytes. We also found that diversity of putative MF was higher in plants from soils with the lowest P levels recorded. Putative mycorrhizal OTUs were predominantly from the Tulasnella lineage, followed by Ceratobasidium and Serendipita. Within a small subset of samples, a difference in colonised endophytes depending on the collection season was observed. In vitro germination studies using 10 OTUs of mycorrhizal fungi in 14 orchid species showed mostly generalist associations. When orchid seed and fungal sources were studied irrespective of habitat, life form, and distance from each other (orchid seed and fungal source), compatibility for symbiotic seed germination was observed in most cases. Issues with the identification of compatible MF and symbiotic system of seed germination are discussed. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Figure 1

15 pages, 5328 KiB

Open AccessArticle

Orchid Extinction over the Last 150 Years in the Czech Republic

by Zuzana Štípková and Pavel Kindlmann

Diversity 2021, 13(2), 78; https://doi.org/10.3390/d13020078 - 13 Feb 2021

Cited by 14 | Viewed by 4211

Abstract

Understanding temporal changes in the distribution and abundance of various species is one of the key goals of conservation biology. During recent decades, the abundance and distribution of many species of plants and animals have declined dramatically, mainly because of habitat loss and [...] Read more.

Understanding temporal changes in the distribution and abundance of various species is one of the key goals of conservation biology. During recent decades, the abundance and distribution of many species of plants and animals have declined dramatically, mainly because of habitat loss and fragmentation. The purpose of this study is to analyze the rate of extinction of orchids at various sites in different 20-year time intervals over the last 150 years, determined according to changes in society. Using the dataset of the orchid records of the Nature Conservation Agency of the Czech Republic, we determined the disappearance rate of orchids from sites using a grid of 1 × 1 km. We found that the vast majority of orchids disappeared from many of their historical localities in all time intervals analyzed. The number of sites suitable for Czech orchids declined by 8–92%, depending on the species. The most threatened orchid species in the Czech Republic are Spiranthes spiralis, Anacamptis palustris, Epipogium aphyllum and Goodyera repens. This all seems to be closely related with changes in agricultural practices in the open as well as in forest habitats. Preserving suitable orchid habitats seems to be the key for keeping Czech orchid flora alive. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Figure 1

15 pages, 1267 KiB

Open AccessArticle

Floral Scent and Pollinators of Cypripedium calceolus L. at Different Latitudes

by Herbert Braunschmid, Robin Guilhot and Stefan Dötterl

Diversity 2021, 13(1), 5; https://doi.org/10.3390/d13010005 - 24 Dec 2020

Cited by 9 | Viewed by 2964

Abstract

Floral scent is an important trait in plant–pollinator interactions. It not only varies among plant species but also among populations within species. Such variability might be caused by various non–selective factors, or, as has been shown in some instances, might be the result [...] Read more.

Floral scent is an important trait in plant–pollinator interactions. It not only varies among plant species but also among populations within species. Such variability might be caused by various non–selective factors, or, as has been shown in some instances, might be the result of divergent selective pressures exerted by variable pollinator climates. Cypripedium calceolus is a Eurasian deceptive orchid pollinated mainly by bees, which spans wide altitudinal and latitudinal gradients in mainly quite isolated populations. In the present study, we investigated whether pollinators and floral scents vary among different latitudes. Floral scents of three C. calceolus populations in the Southern Alps were collected by dynamic headspace and analyzed by gas chromatography coupled to mass spectrometry (GC/MS). These data were completed by previously published scent data of the Northern Alps and Scandinavia. The scent characteristics were compared with information on pollinators recorded for present study or available in the literature. More than 80 scent compounds were overall recorded from plants of the three regions, mainly aliphatics, terpenoids, and aromatics. Seven compounds were found in all samples, and most samples were dominated by linalool and octyl acetate. Although scents differed among regions and populations, the main compounds were similar among regions. Andrena and Lasioglossum species were the main pollinators in all three regions, with Andrena being relatively more abundant than Lasioglossum in Scandinavia. We discuss natural selection mediated by pollinators and negative frequency–dependent selection as possible reasons for the identified variation of floral scent within and among populations and regions. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Figure 1

17 pages, 3789 KiB

Open AccessArticle

Impacts of Forest Thinning and White-Tailed Deer Herbivory on Translocation of the Rare Terrestrial Orchid Platanthera integrilabia

by Savanna Wooten, Geoff Call, Adam Dattilo, Jennifer Cruse-Sanders and Jennifer Nagel Boyd

Diversity 2020, 12(11), 412; https://doi.org/10.3390/d12110412 - 28 Oct 2020

Cited by 3 | Viewed by 3012

Abstract

Translocation is increasingly being used to supplement existing occurrences and establish new occurrences of rare plant species, but translocation success is dependent on understanding responses to habitat conditions and management. Platanthera integrilabia (white fringeless orchid) is a rare terrestrial orchid species presently found [...] Read more.

Translocation is increasingly being used to supplement existing occurrences and establish new occurrences of rare plant species, but translocation success is dependent on understanding responses to habitat conditions and management. Platanthera integrilabia (white fringeless orchid) is a rare terrestrial orchid species presently found in mostly small occurrences that comprise a fraction of its historical distribution and abundance in the southeastern United States. We investigated the influence of shade and white-tailed deer herbivory, as cited concerns for this species, on the early success of its translocation from tubers as determined through measures of emergence, survival, growth, and reproduction of two cohorts. Our findings suggest that translocation from tubers could be a viable option to assist the conservation of P. integrilabia relative to its propagation from seed, but that low early emergence, survival, and flowering rates should be considered in translocation plans. Our results also indicate that translocation and ongoing habitat management should consider the potential for light availability to differentially impact distinct plant life stages and influence deer herbivory. We recommend that additional translocation studies designed to investigate the influence of site conditions on outcomes could improve the success of such efforts as well as inform the management of extant occurrences. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Figure 1

13 pages, 3117 KiB

Open AccessArticle

Impact of Climate Change on the Distribution of Four Closely Related Orchis (Orchidaceae) Species

by Alexandra Evans, Sam Janssens and Hans Jacquemyn

Diversity 2020, 12(8), 312; https://doi.org/10.3390/d12080312 - 13 Aug 2020

Cited by 17 | Viewed by 4971

Abstract

Long-term monitoring programs and population demographic models have shown that the population dynamics of orchids are to a large extent dependent on prevailing weather conditions, suggesting that the changes in climatic conditions can have far reaching effects on the population dynamics and hence [...] Read more.

Long-term monitoring programs and population demographic models have shown that the population dynamics of orchids are to a large extent dependent on prevailing weather conditions, suggesting that the changes in climatic conditions can have far reaching effects on the population dynamics and hence the distribution of orchids. Although a better understanding of the effects of climate change on the distribution of plants has become increasingly important during the final years, only a few studies have investigated the effects of changing temperature and precipitation on the distribution of orchids. In this study, we investigated the impact of climate change on the distribution of four terrestrial orchid species (Orchis anthropophora, Orchis militaris, Orchis purpurea and Orchis simia). Using bioclimatic data for current and future climate scenarios, habitat suitability, range shifts and the impact of different abiotic factors on the range of each species were modelled using Maxent. The results revealed an increase in suitable habitat area for O. anthropophora, O. purpurea and O. simia under each RCP (Representative Concentration Pathway) scenario, while a decrease was observed for O. militaris. Furthermore, all four of the orchids showed a shift to higher latitudes under the three RCPs leading to a significant range extension under mild climate change. Under severe climate change, a significant decline in the distribution area at the warm edge of their distributions was observed. Overall, these results show that mild climate change may be beneficial for the studied orchid species and lead to range expansion. However, continued warming may yet prove detrimental, as all species also showed pronounced declines at lower latitudes when temperature increases were larger than 4 °C. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Graphical abstract

10 pages, 2159 KiB

Open AccessCommunication

Rotating Arrays of Orchid Flowers: A Simple and Effective Method for Studying Pollination in Food Deceptive Plants

by Daniela Scaccabarozzi, Andrea Galimberti, Kingsley W. Dixon and Salvatore Cozzolino

Diversity 2020, 12(8), 286; https://doi.org/10.3390/d12080286 - 22 Jul 2020

Cited by 5 | Viewed by 5662

Abstract

Floral deception has been observed in several genera in angiosperms, but is most common in the Orchidaceae. Pollination mechanisms in food deceptive plants are often difficult to assess, as visitation frequency by insects requires numerous hours of field observations to ascertain. Here, for [...] Read more.

Floral deception has been observed in several genera in angiosperms, but is most common in the Orchidaceae. Pollination mechanisms in food deceptive plants are often difficult to assess, as visitation frequency by insects requires numerous hours of field observations to ascertain. Here, for the first time, we describe in detail and validate a simple and effective method that extends previous approaches to increase the effectiveness of pollination studies of food deceptive orchids. We used an orchid of southwest Australia, Diuris brumalis (Orchidaceae), that visually mimics model plants belonging to the genus Daviesia (Faboideae). Arrays of orchid flowers were placed and moved systematically in proximity to model plants, resulting in rapid attraction of the pollinators of D. brumalis. We compared pollinaria removal (as an indicator of pollination success) in naturally growing orchids with pollinaria removal in arrays of orchid flowers in the same sites. We showed that the proposed method greatly enhances pollinator attractiveness in food deceptive systems with very low pollination rates, and we compared its efficiency with other similar methods. The approach can be used for observing pollinator behavioural patterns and confirming effective pollinators for food deceptive species with low insect visitation rates. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Graphical abstract

15 pages, 2169 KiB

Open AccessArticle

Is the Distribution of Two Rare Orchis Sister Species Limited by Their Main Mycobiont?

by Jacopo Calevo, Samuele Voyron, Enrico Ercole and Mariangela Girlanda

Diversity 2020, 12(7), 262; https://doi.org/10.3390/d12070262 - 30 Jun 2020

Cited by 14 | Viewed by 4279

Abstract

As orchids rely on their mycorrhizal fungi for nutrient supply, their spatial range is dependent on the distribution of orchid mycorrhizal (OM) fungi. We addressed possible correlations between mycorrhizal specificity and the geographic distribution of orchids and OM fungi in three populations of [...] Read more.

As orchids rely on their mycorrhizal fungi for nutrient supply, their spatial range is dependent on the distribution of orchid mycorrhizal (OM) fungi. We addressed possible correlations between mycorrhizal specificity and the geographic distribution of orchids and OM fungi in three populations of the rare sister species Orchis patens and O. canariensis. Metabarcoding of the fungal ITS2 region indicated that, although adult plants of either species were colonized by several ceratobasidioid, tulasnelloid, sebacinoid and serendipitoid fungi, the mycobiont spectra were dominated by Tulasnella helicospora (which occurred in 100% of examined plants with high read numbers), which is a globally distributed fungus. In vitro assays with a T. helicospora isolate obtained from O. patens indicated the effectiveness of this OM fungus at germinating seeds of its native host. At a local scale, higher read numbers for T. helicospora were found in soil samples collected underneath O. patens roots than at locations unoccupied by the orchid. Although these findings suggest that the geographical pattern of the main fungal symbiont does not limit the distribution of O. patens and O. canariensis at this scale, the actual causal link between orchid and OM fungal occurrence/abundance still needs to be better understood. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Graphical abstract

15 pages, 2372 KiB

Open AccessEditor’s ChoiceArticle

Species Diversity of Micromycetes Associated with Epipactis helleborine and Epipactis purpurata (Orchidaceae, Neottieae) in Southwestern Poland

by Rafał Ogórek, Klaudia Kurczaba, Zbigniew Łobas, Elżbieta Żołubak and Anna Jakubska-Busse

Diversity 2020, 12(5), 182; https://doi.org/10.3390/d12050182 - 7 May 2020

Cited by 8 | Viewed by 4589

Abstract

The Orchidaceae family is a diverse family of flowering plants that occur naturally in most parts of the world. However, fungal communities inhabiting different parts of orchids are not sufficiently described. The aim of the study was to conduct a mycological evaluation of [...] Read more.

The Orchidaceae family is a diverse family of flowering plants that occur naturally in most parts of the world. However, fungal communities inhabiting different parts of orchids are not sufficiently described. The aim of the study was to conduct a mycological evaluation of Epipactis helleborine and E. purpurata (Orchidaceae), which grow naturally in Lower Silesia (SW Poland), by identifying the species composition of the culturable micromycetes fungi on the surfaces of the plants and from the inner layers of the tissues. Fungi were identified based on a phenotypic and genotypic analysis. To our knowledge, this is the first such analysis. This study showed that more species of micromycetes were cultured from E. helleborine compared with E. purpurata. The flowering plants of E. helleborine were inhabited by the largest number of culturable fungal species (13 species), and the fewest species were isolated from the flowering plants of E. purpurata (eight species). Some of these fungal species may be pathogens of the plants. The surface tissues of the orchids were mainly inhabited by Mucor moelleri and/or Penicillium biourgeianum. The inner layers of these plants were the most colonized by Alternaria tenuissima and/or Arthrinium arundinis and/or Fusarium sporotrichioides. The relative dominance of these fungal species depended mainly on the development phase of the plants. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Graphical abstract

12 pages, 4302 KiB

Open AccessFeature PaperArticle

Species Richness, Ecology, and Prediction of Orchids in Central Europe: Local-Scale Study

by Matúš Hrivnák, Michal Slezák, Dobromil Galvánek, Jaroslav Vlčko, Eva Belanová, Veronika Rízová, Dušan Senko and Richard Hrivnák

Diversity 2020, 12(4), 154; https://doi.org/10.3390/d12040154 - 17 Apr 2020

Cited by 10 | Viewed by 3768

Abstract

Orchids are one of the most species-rich families in the world, and many species are under threat in numerous countries. Biodiversity research focusing on the relationship between the richness of orchid species and ecological factors was performed across the Cerová vrchovina Mts (Western [...] Read more.

Orchids are one of the most species-rich families in the world, and many species are under threat in numerous countries. Biodiversity research focusing on the relationship between the richness of orchid species and ecological factors was performed across the Cerová vrchovina Mts (Western Carpathians) testing impact of 26 explanatory variables. We aimed to determine the main ecological predictors controlling species richness and to predict potential species richness patterns. Altogether, 19 orchid species were found in the studied area, with Cephalanthera damasonium and Epipactis microphylla being the most common. Four environmental predictors (minimal longitude, carbonate-containing sediments, maximal yearly solar irradiation, and agricultural land) had statistically significant effects on orchid richness following regression analysis. Predictive models for the nine most frequent species using MaxEnt software showed (i) that land cover and geological substrate had the highest contribution to the explained variance in the models and (ii) strong potential for occurrence of given orchids in several poorly mapped parts of the studied area. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Figure 1

12 pages, 957 KiB

Open AccessArticle

Isolation and Identification of Endophytic Bacteria from Mycorrhizal Tissues of Terrestrial Orchids from Southern Chile

by Héctor Herrera, Tedy Sanhueza, Alžběta Novotná, Trevor C. Charles and Cesar Arriagada

Diversity 2020, 12(2), 55; https://doi.org/10.3390/d12020055 - 30 Jan 2020

Cited by 29 | Viewed by 5980

Abstract

Endophytic bacteria are relevant symbionts that contribute to plant growth and development. However, the diversity of bacteria associated with the roots of terrestrial orchids colonizing Andean ecosystems is limited. This study identifies and examines the capabilities of endophytic bacteria associated with peloton-containing roots [...] Read more.

Endophytic bacteria are relevant symbionts that contribute to plant growth and development. However, the diversity of bacteria associated with the roots of terrestrial orchids colonizing Andean ecosystems is limited. This study identifies and examines the capabilities of endophytic bacteria associated with peloton-containing roots of six terrestrial orchid species from southern Chile. To achieve our goals, we placed superficially disinfected root fragments harboring pelotons on oatmeal agar (OMA) with no antibiotic addition and cultured them until the bacteria appeared. Subsequently, they were purified and identified using molecular tools and examined for plant growth metabolites production and antifungal activity. In total, 168 bacterial strains were isolated and assigned to 8 OTUs. The orders Pseudomonadales, Burkholderiales, and Xanthomonadales of phylum Proteobacteria were the most frequent. The orders Bacillales and Flavobacteriales of the phylla Firmicutes and Bacteroidetes were also obtained. Phosphate solubilization was detected in majority of isolates; however, it was significantly higher in Collimonas pratensis and Chryseobacterium sp. (PSI = 1.505 ± 0.09 and 1.405 ± 0.24, respectively). Siderophore production was recorded only for C. pratensis (0.657 ± 0.14 mm day⁻¹), Dyella marensis (0.131 ± 0.02 mm day⁻¹), and Luteibacter rhizovicinus (0.343 ± 0.12 mm day⁻¹). Indole acetic acid production was highly influenced by the isolate identity; however, the significantly higher activity was recorded for Pseudomonas spp. (ranging from 5.507 ± 1.57 µg mL⁻¹ to 7.437 ± 0.99 µg mL⁻¹). Additionally, six bacterial isolates were able to inhibit the growth of some potential plant pathogenic fungi. Our findings demonstrate the potential for plant growth promoting capabilities and some antifungal activities of endophytic bacteria inhabiting the mycorrhizal tissue of terrestrial orchids, which may contribute especially at early developmental stages of orchid seedlings. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Figure 1

35 pages, 4935 KiB

Open AccessArticle

A Comprehensive Study of Orchid Seed Production Relative to Pollination Traits, Plant Density and Climate in an Urban Reserve in Western Australia

by Mark C. Brundrett

Diversity 2019, 11(8), 123; https://doi.org/10.3390/d11080123 - 26 Jul 2019

Cited by 19 | Viewed by 10193

Abstract

The pollination of 20 common terrestrial orchids was studied in a 60-ha urban banksia and eucalypt dominated woodland in Western Australia. Five years of data (24,000 flowers, 6800 plants) measured fruit set relative to floral areas, capsule volumes, climate, phenology, pollination mechanisms, disturbance [...] Read more.

The pollination of 20 common terrestrial orchids was studied in a 60-ha urban banksia and eucalypt dominated woodland in Western Australia. Five years of data (24,000 flowers, 6800 plants) measured fruit set relative to floral areas, capsule volumes, climate, phenology, pollination mechanisms, disturbance tolerance and demography. Pollination varied from 0–95% of flowers, floral displays from 90–3300 mm² and capsules from 15–1300 mm³ per spike. Pollination traits strongly influenced outcomes, with self-pollination highest (59—95%), followed by sexually deceptive autumn or winter-flowering (18–39%), visual deception (0–48%) and sexually deceptive spring-flowering (13–16%). Pollination was limited by drought in autumn or spring and cool winter temperatures. Some orchids were resilient to drought and one formed seed after the leaves withered. Plant density had the greatest impact on fruit set for orchids forming large groups, especially for sexually deceptive pollination. Consequently, small group average (SGA) pollination was up to 4× greater than overall averages and peak seed production occurred in the best locations for genetic exchange and dispersal. SGA rates and seedpod volumes were strongly linked to clonality, but not to demographic trends. Resource competition limited flowering at higher plant densities and competition within spikes resulted in smaller, later-forming seedpods. Pollination data from co-occurring common orchids identified five evolutionary trade-offs linked to pollination, provided baseline data for rare species and revealed impacts of changing climate. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Figure 1

Review

Jump to: Research

25 pages, 2188 KiB

Open AccessReview

The Leafless Vanilla Species-Complex from the South-West Indian Ocean Region: A Taxonomic Puzzle and a Model for Orchid Evolution and Conservation Research

by Cathucia F. Andriamihaja, Aro V. Ramarosandratana, Michel Grisoni, Vololoniaina Jeannoda and Pascale Besse

Diversity 2020, 12(12), 443; https://doi.org/10.3390/d12120443 - 24 Nov 2020

Cited by 12 | Viewed by 5684

Abstract

The pantropical genus Vanilla is a member of the Orchidaceae family, one of the largest and most diverse families of angiosperms in the world. It originated in America and differentiated in America, Africa, and Asia. About 132 species of Vanilla have now been [...] Read more.

The pantropical genus Vanilla is a member of the Orchidaceae family, one of the largest and most diverse families of angiosperms in the world. It originated in America and differentiated in America, Africa, and Asia. About 132 species of Vanilla have now been accepted since the discovery of the genus. Within the Vanilla genus, leaflessness has appeared at least three independent times, in Africa, Asia, and America as an adaptation to drought conditions. The South-West Indian Ocean (SWIO) region, a biodiversity hotspot for orchids, is home to seven leafless species. Chloroplast markers failed to differentiate species within this recent SWIO clade. Morphological traits used for description are very similar between species and do not provide reliable identification. Moreover, some of the species have overlapping flowering periods and geographic distribution in Madagascar, increasing the probability of finding some sympatric species and, therefore, hybrids. Leafless Vanilla species from the SWIO islands are thus an excellent model for understanding the evolution of orchids. For their conservation, and to confirm the identity of these leafless species, an integrated approach with classical taxonomy using a large number of samples, intense fieldwork on biology and ecology, and molecular studies using variable markers is necessary. Full article

(This article belongs to the Special Issue The Ecology and Diversity of Orchids)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

The Ecology and Diversity of Orchids

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (13 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI