Leaf arrangements are invalid in the taxonomy of orchid species

Leaf undulation is used as a diagnostic feature in the taxonomy of different taxa of the Epipactis (Orchidaceae) genus. It is considered a specifically important trait, apart from the column (gynostemium) structure, in the identification of E. muelleri. However, leaf undulation is a common developmental phenomenon in various plants, including orchids, thus the main goal of the research presented was to validate the usefulness of this feature in Epipactis taxonomy. In the course of this study, the leaf structure of six Epipactis species was analyzed, i.e. E. albensis, E. atrorubens, E. helleborine, E. muelleri, E. palustris, and E. purpurata. The leaf margin outline and the cellular pattern of the leaf surface, as well as the presence of papillae, were examined in detail. The results obtained showed that in all taxa analyzed, representing different groups of the Epipactis genus, leaf undulation was present. The phenomenon was related to leaf-blade development and the local differential growth of leaf sectors rather than to the taxonomic position of the species. Therefore, leaf undulation studied in Helleborines, does not have a diagnostic value as a non-programmed intrinsic feature, and should not be applied to the taxa identification. The valid trait in Epipactis classification (including E. muelleri) remains the column structure.

Annales Botanici Fennici, 2017

A wide range of phenotypic variability in the orchid Epipactis purpurata s. stricto was found based on analysis of herbarium material and field research. Twenty-three biometric features were analysed. New diagnostically important features of gynostemium as well as of petal and sepal sizes and colours were established. Thus E. purpurata s. stricto is redescribed, clarifying the taxonomic importance of several morphological features.

Rindyastuti R, Nurfadilah S, Rahadiantoro A, Hapsari L, Abywijaya IK. 2018. Leaf anatomical characters of four epiphytic orchids of Sempu Island, East Java, Indonesia: The importance in identification and ecological adaptation. Biodiversitas 19: 1906-1918. Leaf anatomy features are important characters to support species identification and classification, and they are related to ecological adaptation of species. The aims of the present study were: (i) to investigate leaf anatomical characters of four epiphytic orchids of Sempu Island (Ascochilus emarginatus, Dendrobium subulatum, Thrixspermum subulatum, and Thrixspermum acuminatissimum) in relation to the significance in species identification and ecological adaptation in coastal habitats of Sempu Island, (ii) to compare the adaptive ability of the four species in coastal habitats based on adaptive anatomical characters. The procedure of leaf anatomical studies as follows: orchid leaves were fixed in ethanol 70% and sliced into thin pieces with a microtome, and stained with 1% Safranin. The leaf anatomical organization of orchids (stomata, epidermis, mesophyll, vascular bundles, and other characters such as hypodermis, fibre bundles, raphide bundles, and spiral thickenings) was observed under light microscope. The results showed the comparable data of leaf anatomical characters among the orchids. There was distinct variation in the anatomical characters of the orchids including stomata anomocytic, tetracytic, and cyclocytic; the presence or absence of hypodermis, spiral thickenings, fibre bundles, raphide bundles, and bundle sheaths; homogenous and heterogenous mesophyll; and variation in vascular bundle arrangement. Detailed leaf anatomical characters can be used to distinguish a species from others, which are important to support species identification. The similarity of anatomical characters among these orchids were they possessed relatively thick cuticle and other specific anatomical characters as a structural adaptation to coastal habitat with high irradiation to reduce leaf transpiration. D. subulatum can be considered as the most adaptive orchid species to coastal habitats based on adaptive anatomical characters as it possessed the largest number of adaptive anatomical characters. The implication of this study is the importance of leaf anatomical features to support species identification and to increase understanding of orchid biology and ecology which are important in orchid conservation.

Botanical Journal of …, 2012

A comparative analysis of the main distinctive features of Epipactis pseudopurpurata, according to the protologue, and E. purpurata revealed that the absence or disappearance, as well as the atrophy, of a viscidium is typical and characteristic of young ramets of E. purpurata and can also result from its removal by pollinators and other insect visitors. The gynostemium morphology is similar in both species examined. The minor differences in its shape are an indication of developmental variability. The morphology of numerous ramets of E. purpurata and of their gynostemia corresponds to Mered'a's description of E. pseudopurpurata, suggesting phenotypic plasticity in the former species. Based on comparative analyses of both taxa, including molecular data, the authors propose to synonymize E. pseudopurpurata with E. purpurata in view of the low value of the taxonomic features distinguishing the two species.

PeerJ, 2017

Background and Aims. The charismatic Himantoglossum s.l. clade of Eurasian orchids contains an unusually large proportion of taxa that are of controversial circumscriptions and considerable conservation concern. Whereas our previously published study addressed the molecular phylogenetics and phylogeography of every named taxon within the clade, here we use detailed morphometric data obtained from the same populations to compare genotypes with associated phenotypes, in order to better explore taxonomic circumscription and character evolution within the clade. Methods. Between one and 12 plants found in 25 populations that encompassed the entire distribution of the Himantoglossum s.l. clade were measured in situ for 51 morphological characters. Results for 45 of those characters were subjected to detailed multivariate and univariate analyses. Key Results. Multivariate analyses readily separate subgenus Barlia and subgenus Comperia from subgenus Himantoglossum, and also the early-divergent H. formosum from the less divergent remainder of subgenus Himantoglossum. The sequence of divergence of these four lineages is confidently resolved. Our experimental approach to morphometric character analysis demonstrates clearly that phenotypic evolution within Himantoglossum is unusually multi-dimensional. Conclusions. Degrees of divergence between taxa shown by morphological analyses approximate those previously shown using molecular analyses. Himantoglossum s.l. is readily divisible into three subgenera. The three sections of subgenus Himantoglossumhircinum, caprinum and formosum-are arrayed from west to east with only limited geographical overlap. At this taxonomic level, their juxtaposition combines with conflict between contrasting datasets to complicate attempts to distinguish between clinal variation and the discontinuities that by definition separate bona fide species. All taxa achieve allogamy via food deceit and have only weak pollinator specificity. Artificial crossing demonstrates that intrinsic sterility barriers are weak. Although we have found evidence of gene flow among and within the three sections of subgenus Himantoglossum, reports of natural hybrids are surprisingly rare, probably because putative parents are sufficiently similar to questionably warrant the status of species. Phenological separation and increased xeromorphy characterise the origin of subgenus Barlia. Several individual morphological characters show evidence of parallel acquisition, and loss of features is especially frequent in floral markings among members of How to cite this article Bateman et al. (2017), In situ morphometric survey elucidates the evolutionary systematics of the Eurasian Himantoglossum clade (Orchidaceae: Orchidinae). PeerJ 5:e2893;

Biological Journal of the Linnean Society, 2000

The breeding system is expected to strongly influence the genetic structure of plant populations. In the present study, isozyme variation is documented in Danish populations of three species of Epipactis, varying in breeding system from allogamy to obligate autogamy. The allogamous and widespread E. helleborine subsp. helleborine shows high levels of polymorphism. Most of the genetic variation is found within local populations. A hierarchical analysis indicates significant among-population differentiation, but no regional differentiation in E. helleborine is apparent. This may be due to higher levels of gene flow in the past, before forest was fragmented. The ecotype from coastal dunes, E. helleborine subsp. neerlandica, does not differ from E. helleborine subsp. helleborine in any of the examined loci, but it has a significant population inbreeding coefficient that can probably be explained by higher levels of geitonogamy and the possibility of spontaneous autogamy. The entomophilous E. purpurata and the obligately autogamous E. phyllanthes are monomorphic at all loci examined. Several factors, including a founder effect at the time of colonization, high levels of geitonogamy, as well as habitat specialization combined with erratic flowering may have contributed to the lack of variation in E. purpurata. The lack of variation in the autogamous E. phyllanthes is probably due to inbreeding. It is proposed that autogamy in Epipactis may in some cases have evolved through paedomorphosis of allogamous flowers and that the occurrence of local breeding groups may have facilitated the speciation process.

Botanical Journal of the Linnean Society, 2015

Since the last classification of Orchidaceae in 2003, there has been major progress in the determination of relationships, and we present here a revised classification including a list of all 736 currently recognized genera. A number of generic changes have occurred in Orchideae (Orchidoideae), but the majority of changes have occurred in Epidendroideae. In the latter, almost all of the problematic placements recognized in the previous classification 11 years ago have now been resolved. In Epidendroideae, we have recognized three new tribes (relative to the last classification): Thaieae (monogeneric) for Thaia, which was previously considered to be the only taxon incertae sedis; Xerorchideae (monogeneric) for Xerorchis; and Wullschlaegelieae for achlorophyllous Wullschlaegelia, which had tentatively been placed in Calypsoeae. Another genus, Devogelia, takes the place of Thaia as incertae sedis in Epidendroideae. Gastrodieae are clearly placed among the tribes in the neottioid grade, with Neottieae sister to the remainder of Epidendroideae. Arethuseae are sister to the rest of the higher Epidendroideae, which is unsurprising given their mostly soft pollinia. Tribal relationships within Epidendroideae have been much clarified by analyses of multiple plastid DNA regions and the low-copy nuclear gene Xdh. Four major clades within the remainder of Epidendroideae are recognized: Vandeae/Podochileae/Collabieae, Cymbidieae, Malaxideae and Epidendreae, the last now including Calypsoinae (previously recognized as a tribe on its own) and Agrostophyllinae s.s. Agrostophyllinae and Collabiinae were unplaced subtribes in the 2003 classification. The former are now split between two subtribes, Agrostophyllinae s.s. and Adrorhizinae, the first now included in Epidendreae and the second in Vandeae. Collabiinae, also probably related to Vandeae, are now elevated to a tribe along with Podochileae. Malaxis and relatives are placed in Malaxidinae and included with Dendrobiinae in Malaxideae. The increased resolution and content of larger clades, recognized here as tribes, do not support the 'phylads' in Epidendroideae proposed 22 years ago by Dressler.

The First 100 Years of Research on Barro Colorado: Plant and Ecosystem Science, Vol 2, 2024

ABSTRACT. In this chapter, we review key studies of orchids on Barro Colorado Island (BCI) and consider the history of the place from the context of taxonomic status and eco- logical and evolutionary theory. The contributions are varied yet played a key role in our understanding of orchid taxonomy, pollination, evolution of ant-plant interactions, and plant physiological ecology in epiphytic plants. The demography of epiphytic orchids is described in the context of epiphytism and meta-population dynamics. Along with information on reproduction and gene flow from BCI studies, a distinct characterization emerges of the tempo of evolution in orchids and how this has contributed to the extreme diversity of the group.

Plant Systematics and Evolution, 2009

Epidendrum L. is the largest genus of Orchidaceae in the Neotropical region; it has an impressive morphological diversification, which imposes difficulties in delimitation of both infrageneric and interspecific boundaries. In this study, we review infrageneric boundaries within the subgenus Amphiglottium and try to contribute to the understanding of morphological diversification and taxa delimitation within this group. We tested the monophyly of the subgenus Amphiglottium sect. Amphiglottium, expanding previous phylogenetic investigations and reevaluated previous infrageneric classifications proposed. Sequence data from the trnL-trnF region were analyzed with both parsimony and maximum likelihood criteria. AFLP markers were also obtained and analyzed with phylogenetic and principal coordinate analyses. Additionally, we obtained chromosome numbers for representative species within the group. The results strengthen the monophyly of the subgenus Amphiglottium but do not support the current classification system proposed by previous authors. Only section Tuberculata comprises a well-supported monophyletic group, with sections Carinata and Integra not supported. Instead of morphology, biogeographical and ecological patterns are reflected in the phylogenetic signal in this group. This study also confirms the large variability of chromosome numbers for the subgenus Amphiglottium (numbers ranging from 2n = 24 to 2n = 240), suggesting that polyploidy and hybridization are probably important mechanisms of speciation within the group.

Previous work on orchid seeds has shown that characters associated with the seed coat may be useful for classification and phylogeny at a suprageneric level. The seed morphology of several species of the tribe Chloraeeae was analysed using traditional morphometrics, and the seed shape was studied, for the first time, using tools of geometric morphometrics. Seed characters were evaluated by their discriminative power and the information they may provide in a phylogenetic context. By contrast with previous findings, seed shape resulted in a continuum among the taxa studied, and in only a few cases could genera or groups of species be discriminated on the basis of shape. However, seed size, expressed as centroid size, was a variable character and informative at a phylogenetic level. Traditional measures of seed coat, mainly those of seed coat cells, were also helpful for the discrimination of genera and species, agreeing with previous statements about their utility in taxonomy and phylogeny.