Dactylorhiza Research Articles

Aquatic, riverside-aquatic and shrubswamp vegetation of Bile lake at «Biloozersky» NNP

The territory of the «Biloozerskyi» National Park represents the landscape complexes of the Middle Dnipro region, the integral elements of which contain ancient watercourses, swampy and waterlogged, wedged between the raised segments of the pine terrace and often connected to the modern floodplain. In the central part of such a decline (89–92 m above sea level), which is located within the park, there is a floodplain Bile Lake with a swampy island, which divides it into a smaller eastern water area of the lake and a larger western one. The periphery of the lake is surrounded by areas of swampy shores. The total area of flooded and swampy areas is about 16 hectares, of which the area of the water pond is 9 hectares. Considerable areas are represented by thickets of air-water vegetation and swamp-bog swamps with a thick cover of Sphagnum sp. The water supply of this lake is complex and is provided by both the underground waters of the pine terrace and the waters of the surface runoff. And in the presence of a swampy decline with channels connecting them into one wetland system, they provide the possibility of slow water exchange between the Kaniv Reservoir and the lake. The examined territory has a fairly rich and diverse plant complex. A number of habitats protected by Directive 92/43/EU «On the conservation of natural habitats and species of natural fauna and flora» are presented and large populations of two species of marsh orchids (Liparis loeselii (L.) Rich., Epipactis palustris (L.) Crantz) and water fern (Salvinia natans (L.) All.) are listed in the Red Book of Ukraine (2009). In addition, three species protected in the Kyiv region grow here in the conditions of natural biotopes (Drosera rotundifolia L., Dryopteris cristata (L.) A. Gray, Nymphaea alba L.).

Fungal Community Composition at the Last Remaining Wild Site of Yellow Early Marsh Orchid (Dactylorhiza incarnata ssp. ochroleuca).

The yellow early marsh orchid (Dactylorhiza incarnata ssp. ochroleuca) is a critically endangered terrestrial orchid in Britain. Previous attempts to translocate symbiotic seedlings to a site near the last remaining wild site demonstrated some success, with a 10% survival rate despite adverse weather conditions over a two-year period. However, to facilitate future reintroduction efforts or conservation translocations, a more comprehensive understanding of the fungal microbiome and abiotic soil characteristics at the final remaining wild site is required. Obtaining comprehensive information on both the fungal community and soil nutrient composition from wild sites has significant benefits and may prove critical for the success of future conservation translocations involving threatened orchids. This preliminary study, conducted at the last remaining wild site, revealed a significant correlation between the relative abundance of the orchid mycorrhizal fungal order Cantharellales and the concentrations of nitrate and phosphate in the soil. Another orchid mycorrhizal fungal group, Sebacinales, was found to be distributed extensively throughout the site. The composition of fungal communities across the entire site, orchid-hosting and non-orchid-hosting soils is discussed in relation to reinforcing the current population and preventing the extinction of this orchid.

Recurrent allopolyploidizations diversify ecophysiological traits in marsh orchids (Dactylorhiza majalis s.l.).

Whole-genome duplication has shaped the evolution of angiosperms and other organisms, and is important for many crops. Structural reorganization of chromosomes and repatterning of gene expression are frequently observed in allopolyploids, with physiological and ecological consequences. Recurrent origins from different parental populations are widespread among polyploids, resulting in an array of lineages that provide excellent models to uncover mechanisms of adaptation to divergent environments in early phases of polyploid evolution. We integrate here transcriptomic and ecophysiological comparative studies to show that sibling allopolyploid marsh orchid species (Dactylorhiza, Orchidaceae) occur in different habitats (low nutrient fens vs. meadows with mesic soils) and are characterized by a complex suite of intertwined, pronounced ecophysiological differences between them. We uncover distinct features in leaf elemental chemistry, light-harvesting, photoprotection, nutrient transport and stomata activity of the two sibling allopolyploids, which appear to match their specific ecologies, in particular soil chemistry differences at their native sites. We argue that the phenotypic divergence between the sibling allopolyploids has a clear genetic basis, generating ecological barriers that maintain distinct, independent lineages, despite pervasive interspecific gene flow. This suggests that recurrent origins of polyploids bring about a long-term potential to trigger and maintain functional and ecological diversity in marsh orchids and other groups.

Systematic reappraisal of marsh-orchids native to Scotland

SummaryThe intensively studied Eurasian orchid genus Dactylorhiza has become a model system for exploring allopolyploid evolution, yet determining the optimal circumscriptions of, and most appropriate ranks for, its constituent taxa remain highly controversial topics. Here, novel allozyme data and detailed morphometric data for 16 Scottish marsh-orchid populations are interpreted in the context of recent DNA sequencing studies. Despite being derived from the same pair of parental species, the two allopolyploid species that currently occur in Scotland can reliably be distinguished using allozymes, haplotypes, ribotypes or sequences of nuclear genes. A modest range of diverse morphological characters are shown to distinguish the two molecularly-circumscribed species, but they have in the past been obscured by equivalent levels of infraspecific variation in characters rooted in anthocyanin pigments; these characters are better employed for distinguishing infraspecific taxa. Dactylorhiza francis-drucei (formerly D. traunsteinerioides) is confirmed as being distinct from the continental D. traunsteineri/lapponica, probably originating through allopatric isolation once the continental lineage reached Britain. All Scottish populations are attributed to the comparatively small-flowered, anthocyanin-rich subsp. francis-drucei, which includes as a variety the former D. 'ebudensis'; the less anthocyanin-rich subsp. traunsteinerioides is confined to Ireland, North Wales and northern England. In contrast with D. francis-drucei, only a minority of Scottish populations of D. purpurella are attributed to the anthocyanin-rich race, var. cambrensis. This species most likely originated through an allopolyploidy event that occurred comparatively recently within the British Isles, as it contains allozyme alleles distinctive of British rather than continental D. incarnata (its diploid pollen-parent). In contrast, the rare Scottish population of D. incarnata subsp. cruenta shares with its Irish counterparts a continental genotype, and is most likely a recent arrival in Scotland through long-distance dispersal. Among all European allotetraploid dactylorchids, D. purpurella is the species that most closely resembles D. incarnata, both molecularly and morphologically.

New and Noteworthy Taxa of the Genus Dactylorhiza Necker ex Nevski (Orchidaceae Juss.) in Kazakhstan Flora and Its Response to Global Warming

A critical study of the herbarium material representing the orchid genus Dactylorhiza Necker ex Nevski in Kazakhstan was conducted in 2019–2020. The information on the species composition was clarified. Dactylorhiza fuchsii subsp. hebridensis (Wilmott) Soó and D. × kerneri (Soó) Soó were identified for the first time in the country. New taxa were noted for individual botanical and geographical areas. All taxa were presented in the list and annotated with studied herbarium materials from the Kazakhstan area. Based on the collected and available locations for the studied taxa, distribution modeling was carried out for the four taxa (D. incarnata, D. majalis subsp. baltica, D. salina, and D. umbrosa). Bioclimatic data for the present and future (2041–2060) based on four possible scenarios were used. The occurrence of Dactylorhiza representatives in Kazakhstan is threatened by global climate warming. It is likely that some of them may not occur in the country in the future (D. incarnata and D. majalis subsp. baltica), losing up to 99.87% of their modern range or their range may be significantly reduced (D. salina and D. umbrosa), losing up to 80.83% of their present distribution. It is worth considering global changes in planning conservation activities and identifying areas that may play a significant role in the functioning of the national flora in the future.

Dactylorhiza maculata species aggregate (Orchidaceae: Orchidoideae) in Murmansk Region (North European Russia): morphological delimitation of plants with different ploidy level

As a result of studies of the genus Dactylorhiza undertaken by Alexey B. Shipunov, numerous "northern tetraploids" – plants combining the genomes of diploid D. fuchsii and tetraploid D. maculata s.str., were found among the material from North European Russia. However, it remained unclear whether non-hybrid D. fuchsii was represented in the northern part of the genus' range, as well as what the morphological distinctive features of plants with different ploidy levels were. Cariology and morphometric studies on material from the Murmansk Region showed that both diploid (2n=40) and tetraploid (2n=80) plants occur here, and plants with different ploidy, as a rule, do not occur together. Diploids were associated with D. fuchsii, but their high morphological similarity with tetraploids was noted, apparently due to the smoothing of morphological differences in "northern tetraploids", as well as due to the weak ecological divergence of species of the genus Dactylorhiza in the northern part of their range. The best distinguishing features of plants with different ploidy, established by methods of mathematical statistics, are considered in detail in the paper.

Integrative Study Supports the Role of Trehalose in Carbon Transfer From Fungi to Mycotrophic Orchid.

Orchids rely on mycorrhizal symbiosis, especially in the stage of mycoheterotrophic protocorms, which depend on carbon and energy supply from fungi. The transfer of carbon from fungi to orchids is well-documented, but the identity of compounds ensuring this transfer remains elusive. Some evidence has been obtained for the role of amino acids, but there is also vague and neglected evidence for the role of soluble carbohydrates, probably trehalose, which is an abundant fungal carbohydrate. We therefore focused on the possible role of trehalose in carbon and energy transfer. We investigated the common marsh orchid (Dactylorhiza majalis) and its symbiotic fungus Ceratobasidium sp. using a combination of cultivation approaches, high-performance liquid chromatography, application of a specific inhibitor of the enzyme trehalase, and histochemical localization of trehalase activity. We found that axenically grown orchid protocorms possess an efficient, trehalase-dependent, metabolic pathway for utilizing exogenous trehalose, which can be as good a source of carbon and energy as their major endogenous soluble carbohydrates. This is in contrast to non-orchid plants that cannot utilize trehalose to such an extent. In symbiotically grown protocorms and roots of adult orchids, trehalase activity was tightly colocalized with mycorrhizal structures indicating its pronounced role in the mycorrhizal interface. Inhibition of trehalase activity arrested the growth of both symbiotically grown protocorms and trehalose-supported axenic protocorms. Since trehalose constitutes only an inconsiderable part of the endogenous saccharide spectrum of orchids, degradation of fungal trehalose likely takes place in orchid mycorrhiza. Our results strongly support the neglected view of the fungal trehalose, or the glucose produced by its cleavage as compounds transported from fungi to orchids to ensure carbon and energy flow. Therefore, we suggest that not only amino acids, but also soluble carbohydrates are transported. We may propose that the soluble carbohydrates would be a better source of energy for plant metabolism than amino acids, which is partially supported by our finding of the essential role of trehalase.

Challenges of applying monophyly in the phylogenetic shallows: taxonomic reappraisal of the Dactylorhiza maculata group

SummaryThe first study of the taxonomically critical European orchid genus Dactylorhiza to use next-generation DNA sequencing generated the statistically best-supported reconstruction of its phylogeny to date. However, the two competing topologies obtained within the monophyletic Section Maculatae differed radically in the placement of the D. maculata s.s.–D. foliosa clade. Both topologies showed D. foliosa to be nested deeply within D. maculata s.s., and suggested that D. saccifera s.l. is paraphyletic, D. saccifera s.s. from south-eastern Europe and Asia Minor diverging before D. gervasiana from south-central Europe (a taxon typically viewed as a subspecies of D. saccifera or, more often, ignored completely). The poorly-sampled but character-rich morphometric comparison presented here suggests that D. saccifera s.s. and D. gervasiana cannot be distinguished with confidence using morphological characters and that, if D. gervasiana is accepted as a species, it is effectively cryptic. The diploid D. foliosa is accepted as an island endemic species, despite rendering paraphyletic the autotetraploid D. maculata s.s.; all other named taxa within the D. maculata s.s. clade are considered infraspecific. Dactylorhiza fuchsii is indisputably a bona fide species rather than a subspecies but it does not merit becoming the basis of a taxonomic section separate from D. maculata s.s. The strongly contrasting degrees of molecular vs morphological disparity reported here are representative of a more general trend evident in groups that have experienced comparatively recent speciation, as is the need to recognise occasional paraphyletic species when circumscribing species by integrating genotypic and phenotypic data categories. Explicit taxonomic criteria combined with a comparative, monographic approach are needed to achieve consistency of ranking. Disproving hypotheses of species status is judged a criminally underrated activity, actually being as important to outcomes as much-vaunted species "discovery".

Flower morphometry of members of the genus Dactylorhiza Necker ex Nevski (Orchidaceae) from the Altai Mountains of Kazakhstan

Abstract. Sumbembayev AA, Abugalieva SI, Danilova AN, Matveyeva EV, Szlachetko DL. 2021. Flower morphometry of members of the genus Dactylorhiza Necker ex Nevski (Orchidaceae) from the Altai mountains of Kazakhstan. Biodiversitas 22: 3545-3555. Several species of Dactylorhiza (Orchidaceae) from the Altai mountains of Kazakhstan have been investigated regarding their morphological flower variability. Significant metric characters were identified allowing to differentiate between the four species: D. incarnata, D. fuchsii, D. maculata and D. salina. The morphometric structure of flowers was analyzed by comparing 17 metric parameters in representatives of 11 populations. We identified the most variable and stable traits as well as distinctive features for each species. A high degree of flower morphometric diversity was revealed from principal component analysis for species and populations. Cluster analysis demonstrated the structure of the population diversity. Structural schemes have been compiled from data of the photographic processing of flower morphometry, the analysis of variance ANOVA, and the degree of variation at the population level. Useful characters are provided for further taxonomic work on members of the genus Dactylorhiza in Kazakhstan.

PRIMARY INTRODUCTION RESULTS OF THE GENUS DACTYLORHIZA NECKER EX NEVSKI IN THE ALTAI BOTANICAL GARDEN

The primary introduction resulted in a stable collection of 4 species of the genus Dactylorhiza: D. fuchsii (Druce) Soo, D. incarnata (L.) Soo, D. maculata (L.) Soo, D. umbrosa (Kar. & Kir.) Nevski. Individuals of D. incarnata showed plasticity and good adaptability to conditions of culture. Their morphometric indicators of the length of the inflorescence increased by 14%, and the number of flowers in the inflorescence by 52%, indicators of the length and width of the basal leaves by 108% and 23% respectively. The results of the study have of great importance for the development of introduction agricultural technology of rare and endangered plants in the mountain taiga zone of East Kazakhstan, contribute to the preservation of biodiversity. Due to the short-term observation, more detailed analyzes of the results will be obtained with the further continuation of the introduction experiment.

New intergeneric orchid hybrid found in Romania × Pseudorhiza nieschalkii (Senghas) P.F.Hunt nothosubsp. siculorum H.Kertész & N.Anghelescu, 2020.

We describe the first reported intergeneric, which naturally occurs between two subspecies belonging to different genera, Dactylorhiza fuchsii subsp. sooana (genus Dactylorhiza) and Pseudorchis albida subsp. tricuspis (genus Pseudorchis), as × Pseudorhiza nieschalkii (Senghas) P.F.Hunt nothosubsp. siculorum H.Kertész & N.Anghelescu, 2020. The hybrid was found and digitally photographed for the first time by Hajnalka Kertész in June, 2020, within Terra Siculorum, in one of the Natura 2000 protected areas, known as Harghita Mădăraș, ROSCI00090. Following detailed morphometric analysis using 67 characters and molecular karyological analyses, we identified this unique specimen as an intergeneric hybrid, new to science. The hybrid, an F1 generation plant, most likely representing a single intergeneric pollination event, is phenotypically intermediate between its parental species in most of the characters scored, but it significantly closely resembles Pseudorchis albida subsp. tricuspis parent. Since several individuals of the parental species occurred in near proximity, within 1–10 meters distance, we suggest that the production of this hybrid required a minimum travel distance of ca 1–10 meters, by the pollinators and frequent exchange of pollen between the parental species was very likely. The parental species and the hybrid, which display a considerable synchronicity in their flowering time, overlap in the pollinator community, sharing various species of Hymenopterans and Dipterans, very abundant in the heathland. This Terra Siculorum hybrid is thus best described as a rarely occurring intergeneric hybrid that shows strong Pseudorchis albida subsp. tricuspis parental dominance in inheritance patterns.

Asymmetric contributions of seed and pollen to gene dispersal in the marsh orchid Dactylorhiza umbrosa in Asia Minor.

Orchids differ from other plants in their extremely small and partly air-filled seeds that can be transported long distances by wind. Seed dispersal in orchids is expected to contribute strongly to overall gene flow, and orchids generally express low levels of genetic differentiation between populations and low pollen to seed flow ratios. However, studies in orchids distributed in northern Europe have often found a poor geographic structuring of genetic variation. Here, we studied geographic differentiation in the marsh orchid Dactylorhiza umbrosa, which is widely distributed in upland regions from Asia Minor to Central Asia. These areas were less affected by Pleistocene ice ages than northern Europe and the orchid should have been able to survive the last ice age in local refugia. In the plastid genome, which is dispersed by seeds, populations at close distance were clearly divergent, but the differentiation still increased with geographic distance, and a significant phylogeographic structure had developed. In the nuclear genome, which is dispersed by both seeds and pollen, populations showed an even stronger correlation between genetic and geographic distance, but average levels of differentiation were lower than in the plastid genome, and no phylogeographic structure was evident. Combining plastid and nuclear data, we found that the ratio of pollen to seed dispersal (mp/ms) decreases with physical distance. Comparison with orchids that grow in parts of Europe that were glaciated during the last ice suggests that a balanced structure of genetic diversity develops only slowly in many terrestrial orchids, despite efficient seed dispersal.

Geographical distribution and ecological-phitocenotic features of orchids of the Southern Altai in the Kazakh Altai

According to the results of the study, 14 species of orchids were found in the flora of the southern Altai in2019, which is 52 % of the species diversity of the Orchid flora of Kazakhstan. It is established that the coenopopulationsof orchids in the region develop and exist within the boundaries of specific phytocenoses and are characterized by a certainecological and phytocenotic amplitude of the development of natural environment conditions. They are distributed in thelower, middle and upper mountain zones. The widest altitude range is typical for species from the genus Dactylorchiza(absolute altitude 462–1365 m). In terms of life forms, species with a stem-like tuberoid (genera Dactylorhiza, Herminium,Orchis) predominate, while short-rooted and long-rooted species (genera Cypripedium, Epipactis) are less represented. InKaton-Karagai district, 10 species of orchids were recorded growing in 19 cenopopulations, in Kurchum – 5 species in 6cenopopulations. Vegetation cover in habitats is formed from 35 to 90 %. Due to the weak competition of orchids, theirshare in the addition of phytocenoses does not exceed 2 %.

<p><strong>Typification of the names <em>Epilobium lanceolatum</em>, <em>Lotus requienii</em>, <em>Orchis romana</em>, and <em>Romulea columnae</em> described from Rome (Italy)</strong></p>

The names Epilobium lanceolatum, Lotus requienii (currently accepted as Lotus conjugatus subsp. requienii), Orchis romana (currently accepted as Dactylorhiza romana subsp. romana), and Romulea columnae are lectotypified on specimens kept at RO and BOLO, and on a Sebastiani’s illustration published in his Romanarum plantarum fasciculus primus. An epitype (at RO) for the name Epilobium lanceolatum is also designated.

Comparison of labellum and spur papillae in Dactylorhiza (Orchidaceae) from Anatolia

This study aimed to compare the labellum and spur papillae and also the papillae types as taxonomic characters to circumscribe taxa of the genus Dactylorhiza Necker ex Nevski distributed in Anatolia (Turkey). Plant samples were collected from different regions of Anatolia, especially the Black Sea Region. Ten species were examined using light and scanning electron microscopy. The papillae and epidermis cell size of the taxa were measured and statistically compared. The papillae of the labellum were morphologically similar among the species, except for the surface striation. Spur papillae are different from the labellum papillae. Dactylorhiza characteristics such as labellum papillae shape and surface ornamentation, spur papillae shape, spur shape, and spur/ovary rate are relevant for the taxonomy of the genus.

The complete chloroplast genome sequence of Dactylorhiza majalis (Rchb.) P.F. Hunt et Summerh. (Orchidaceae)

The complete chloroplast genome of Dactylorhiza majalis (Rchb.) P.F. Hunt et Summerh. (Orchidaceae:Orchidoideae) was assembled and characterized using next-generation sequencing data. The plastome (154,108 bp) possesses the typical circular structure consisting of a large single-copy region (LSC; 83,196 bp), a small single-copy region (SSC; 26,580 bp), and two copies of inverted repeats (17,752 bp each). Its overall GC content is 36.99% and the plastome encodes 134 genes. Reconstruction of phylogenetic relationships using complete plastome sequences of Orchidaceae representatives showed that D. majalis was nested within the Orchidoideae tribe Orchideae. The complete plastome comprises a valuable tool in elucidating taxonomic uncertainties within the genus Dactylorhiza.

The genus <i>Cypripedium</i> L. in the unique habitat of orchids in the Novosibirsk Region

This paper provides information about the unique habitat, where 13 species of orchids of the genera Dactylorhiza Nevski, Epipactis Zinn, Gymnadenia R. Br., Herminium R. Br., Orchis L., Platanthera L.C.M. Rich., Cypripedium L. grow in Iskitim District of the Novosibirsk Region. A morphological description of three kinds of shoes is given, including a new for the Novosibirsk Region species Cypripedium ventricosum Sw., which is proposed to be included in the Red Book of the Novosibirsk Region. The investigated community of shoes is located in a birch-high-herbage forest, in the Koyniha river basin. Comparison of the characteristics of the vegetative and generative organs Cypripedium x ventricosum Sw., Cypripedium calceolus L. and Cypripedium macranthon Sw, described as a result of monitoring, is compared with literary data. It was shown that all parameters of C. calceolus, except for the bract length (greater than average), are included in the described range. In the studied habitat, most of the parameters of C. macranthon and C. ventricosum (the length and width of the bract, the length and width of the lateral leaf of the perianth of the inner circle) have higher values. It allows us to conclude that the eco-cenotic conditions of the studied habitat are most favorable for C. macranthon and C. ventricosum. Cenopopulations of all three species exist for a fairly long period and are in their real optimum.

Demographic responses to climate variation depend on spatial- and life history-differentiation at multiple scales

Long-term demographic data are needed for detailed viability analyses of populations threatened by climate change, but the infeasibility of obtaining such data makes it urgent to assess whether demographic responses to climatic variation can be generalized across populations and species. We used 32 years of demographic data on four species of closely related orchids (genera Dactylorhiza and Gymnadenia), replicated in a coastal and an inland region in central Norway, to test how demographic responses to climate varied among geographical regions and species. We fit generalized linear mixed models (GLMMs) to study climate effects on vital rates and included GLMMs as components in matrix models to examine climate effects on population dynamics. We found that, overall, vital rates and population growth rates of the eight populations responded independently to variation in both temperature and rainfall. Only probability of flowering showed expected regional differentiation in response to climate, despite notable regional climatic differences. Other vital rate – climate relationships were structured by species or a combination of both region and species. The weak clustering of demographic responses to climate variation by species and region demonstrates that effects of climatic variation can strongly depend on variation in local habitat and life history, even among closely related populations occupying similar niches. This highlights the difficulty in transferring data from closely related and/or located populations for viability analyses and for models predicting range shifts, and a general need to account for among-population variation in demographic responses to develop successful conservation and management plans.

Orchid colonization: multiple parallel dispersal events and mosaic genetic structure in Dactylorhiza majalis ssp. lapponica on the Baltic island of Gotland.

The island of Gotland in the Baltic Sea has had no contact with surrounding continental areas since the withdrawal of the Weichselian ice sheet at approx. 17 ka BP. Plants present on Gotland must have arrived by long-distance dispersal, so populations are expected to exhibit reduced levels of genetic diversity compared with populations on surrounding mainlands. However, orchids have very small seeds, which appear well adapted to long-distance dispersal, and they should therefore be less affected than other plant species by colonization bottlenecks. The aim of this study was to analyse the genetic structure of orchids colonizing isolated islands, using the marsh orchid Dactylorhiza majalis ssp. lapponica as a case study. More than 500 samples from 27 populations were analysed for 15 plastid and eight nuclear marker loci. Population diversity and differentiation patterns were compared for nuclear and plastid marker systems and analysed in relation to geographical location. We found high genetic diversity but no clear geographical structure of genetic differentiation between populations on Gotland. However, the between-population differentiation in plastid and nuclear markers were correlated and the greatest diversity was found at sites at comparatively high elevations, which were the first to emerge above the water after the Ice Age. The regional population on Gotland has been established by a minimum of four dispersal events from continental regions. Subsequent gene flow between sites has not yet homogenized the differentiation pattern originating from initial colonization. We conclude that long-distance seed dispersal in orchids has a strong impact on structuring genetic diversity during periods of expansion and colonization, but contributes less to gene flow between populations once a stable population structure has been achieved.

High levels of genetic diversity in marginal populations of the marsh orchid Dactylorhiza majalis subsp. majalis

Because of harsh conditions, suboptimal habitat quality and poor connectivity to other populations, plant populations at the margin of a distribution are expected to be less genetically diverse, but to be more divergent from each other than populations in the centre of a distribution. In northern Europe, northern marginal populations may also be younger than populations further to the south, and may have had less time to accumulate genetic diversity by mutation and gene flow. However, orchids have very small seeds, which are easily dispersed long distances by wind, and orchids are therefore expected to show less differentiation between marginal and central populations than other groups of seed plants. Here, we analysed whether Scandinavian populations of the tetraploid marsh orchid Dactylorhiza majalis subsp. majalis differ from central European populations in genetic diversity patterns. A total of 220 plants from eight central European and ten Scandinavian populations was examined for variation at five nuclear microsatellite loci, nuclear ITS and 13 polymorphic sites in noncoding regions of the plastid genome. The total genetic diversity was slightly lower in Scandinavia than in central Europe, both in plastid and nuclear markers, but the differences were small. Also, the Scandinavian populations were less diverse and somewhat more strongly differentiated from each other than the central European ones. Dactylorhiza majalis subsp. majalis has apparently colonized Scandinavia on multiple independent occasions and from different source areas in the south. Seed flow between Scandinavian populations has still not fully erased the patterns imprinted by early colonization. Our results suggest that marginal populations of orchids may be as important as central ones in preserving genetic diversity through Pleistocene glacial cycles. We also predict that orchids with their light seeds are better adapted than many other plants to respond to future climate changes by dispersing into new suitable areas.