New insights into the classification of Cymbidium
By Dr David Du Puy - Botanisches Institut des Universität - Bâle, Suisse

Molecular systematic studies of the genus Cymbidium have given added insights into the infrageneric classification of the genus. In most cases the results agree with the classification proposed by Du Puy and Cribb in1988, based on morphological and anatomical studies. The main area where molecular systematic studies have helped is in resolving the relationships within the heterogeneous subgenus Cymbidium: the other two subgenera Cyperorchis and Jensoa remain almost as they were originally defined. Within subgenus Cymbidium, the groupings of the Asian and Australian species have been clarified, and there may be evidence to support the splitting of this paraphyletic group into two subgenera. The genus is shown to have had its origins in south-east Asia, and although the Australian species have been poorly represented in these studies, there are indications of their relationship to the Asian section Cymbidium. Molecular analyses have also clarified the affinities of some of the species which were originally difficult to classify with any certainty, and which were recognised as monospecific sections. Surprisingly, the molecular data infer that C. dayanum should be moved to a different subgenus. However, they are very confused concerning the correct classification of C. devonianum. It is frustrating that these analyses do not include all of the species: the results are incomplete and it is impossible to construct a full new classification, or to debate the inferred relationships, until the gaps in critical areas are filled.

Dr. David Du Puy is a Scottish botanist specialising in the Orchidaceae, the flora and vegetation of Madagascar, and conservation. He has published ‘The Genus Cymbidium’ (1988), ‘The Orchids of Madagascar’ (1999), and ‘The Leguminosae of Madagascar’ (2004). He is currently Keeper of the Jany Renz Herbarium in Basel, Switzerland.

The contribution of DNA to our understanding of the evolution and natural classification of European orchids
By Professor Richard M Bateman - Department of Botany, Natural History Museum, London U.K


DNA-based studies are revolutionising our perspective on orchid evolution, and on any system of classification that aims to represent evolutionary relationships. When viewed from the side, evolution is best represented as a phylogenetic tree that depicts time, with the first ever orchid located at the base of the trunk and each living species occupying the tip of an individual branch. When viewed from above, we see only living species but we can achieve greater focus, aggregating individuals into populations and populations into species. Both types of approach are most effective if information from “traditional” morphology and from DNA-based analyses are gathered simultaneously from the same set of orchid plants, as it is the causal relationship between genes, appearance and geographic location that best describes orchid evolution; this in turn feeds into classification, and this in turn informs conservation priorities. Increasingly sophisticated studies of European orchids are demonstrating that some morphologically-delimited species are “Emperor’s New Clothes” species that lack genetic cohesion and should therefore be abandoned. In contrast, “Cinderella” species have not previously been recognised morpohologically but have strong genetic cohesion and so merit wider recognition. Systematitsts are having even more difficulty classifying orchid populations that are actively evolving, either through geographic isolation (“Robinson Crusoe” species) or through radical change in appearance due to mutation (“Rumplestiltskin” species). Pessimists view the current situation of controversial systematic changes as confusing and unwelcome, whereas optimists perceive recent research as insightful and exciting, recognising that this rapid increase in knowledge favours the orchids over other less charismatic plant families and will eventually lead to a more logical and stable classification.

Professor Richard M Bateman studies the relationship between systematics and speciation processes in orchids. He heads the only research department in Britain still calling itself “Botany”; he is also an Honorary Professor at the University of Reading, Honorary Research Fellow at the Royal Botanic Gardens Kew, and a former President of the UK Hardy Orchid Society.

Towards an Understanding of the Diversification of the genus Epidendrum
By Eric Hágsater and Miguel Soto - Herbario AMO - México


The genus Epidendrum is probably the largest, monophyletic genus of Neotropical orchids. In the last years we have inferred a molecular phylogeny of it and its related taxa: Microepidendrum, Orleanesia, Barkeria and Caularthron. Epidendrum may have had an early diversification in Mesoamerica and descent from sympodial, pseudobulbous relatives of seasonal climates. We have mapped in the Epidendrum phylogeny some vegetative traits that we hypothesize had a significant role in the huge diversification of this group, such as the monopodial habit, the monocarpic behavior (semelparity), the presence of dimorphic shoots specialized either in vegetative growth or reproduction, and the loss of a pre-determined renewal bud in sympodial species. These traits seem to be adaptative and could have permitted the successful colonization of the epiphytic biotope of the wet Andean forests of South America, where the genus has reached at present its highest diversification.
Floral characters in Epidendrum seem to be highly associated with the pollination systems and pollen vectors. Comparative analysis with non-directional methods were conducted to evaluate the parallel evolution of some traits, especially those that conform the Sphingid pollination syndrome, and to show its independent evolution in different lineages of the genus. The diversification of the clades pollinated by lepidopters that seek pyrrolizidine alkaloids is discussed in a phylogenetic framework.

New ideas on the classification of Dendrobium
By Dr Mark A. Clements - Centre for Plant Biodiversity Research - Australia


Published results from molecular research, using DNA sequences of the internal transcribed spacer (ITS) region of the 18-26S nuclear ribosomal repeat unit, plastid DNA genes, coupled with detailed morphological, biological and developmental studies, using a broadly representative sample of species have provided a very strong basis for the phylogenetic reassessment of the Dendrobium sens. lat. and allied taxa where: (a) sect. Oxystophyllum is deeply embedded within the outgroup taxon, subtribe Eriinae: Podochileae; and (b) the remaining taxa constitute the Dendrobieae which comprises three major monophyletic taxa now formally recognized as the subtribes Epigeneiinae, Dendrobiinae and Grastidiinae. With the historically accepted, easily recongised and well defined genera Cadetia, Diplocaulobium and Flickingeria, all deeply embedded within the Grastidiinae, this also renders the traditional concept of Dendrobium polyphyletic. These studies confirm that it is the predominantly vegetative synapomorphic characters rather than floral characters, that define monophyletic groups within the subtribes. The recognition of these groups as genera is phylogenetically more informative and predictive than any of the alternatives.

Dr Mark A. Clements is a Research Scientist at the Centre for Plant Biodiversity Research/Australian National Herbarium in Canberra, Australia specialising in research on the phylogenetics and biology of the Australasian Orchidaceae with special emphasis on the Dendrobieae and on orchid fungus relationships.




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