Monocots III: Orchids
Recent Achievements
Collections (2001-2005)
Upgrade of the living collections has occurred through acquisition of critical material of known provenance.
Gap-filling in the Herbarium orchid collection has continued from Kew’s own expeditions and by exchange with other CITES registered institutions. The databasing and scanning of the type specimens, which number over 30,000, has progressed well, and all the African types are now databased (2,452). The Herbarium collections continue to be reorganised in line with Genera Orchidacearum’s new classification of the family.
The Micropropagation Unit have stored over 4,000 seed accessions of 1,200 orchid species, from about 270 genera. This includes accessions that are no longer represented in the living collections, which we aim to grow to provide replacements.
The DNA Bank at RBG Kew contains 4,225 orchid accessions, and this is being expanded as rapidly as possible as part of the international Tree of Life project to improve our understanding of orchid phylogenetics and evolution. British terrestrial orchids are an important component of this collection, and for some rare and endangered British orchids we hold nearly complete population samples for all known populations.
Baseline Plant Diversity Research (2001-2005)
The World Checklist of Orchids has been available as a web-searchable database since early 2005. It has rapidly been adopted as the standard list by other institutions, orchid societies and conservation bodies. Considerable progress has been made in baseline research on Old World orchids. Our African Flora projects are now complete with the publication of a Field Guide to Ethiopian Orchids (2003). The 2nd edition of the annotated and illustrated checklist of The Orchids of Madagascar (1999) is in press. The Orchids of Bhutan (732 species) was published in 2002. The publication of The Orchids of Sumatra (2001) marked the first account of this rich orchid flora of over 1,500 species. The Orchids of Borneo series progressed with the publication of volume 4 in 2003. The Orchids of Mt Kinabalu (820 species) is in press.
Three monographs have been completed: The Slipper Orchids of Vietnam (2003), The Genus Coelogyne (2002), and The Genus Cymbidium (in press).
Comparative Plant Biology (2001-2005)
The programme in orchid phylogenetics and evolution has produced a large number of papers that have focused on poorly understood orchid subfamilies, tribes and subtribes. These include subfamilies Cypripedioideae and Vanilloideae (published prior to 2001) and Arethuseae (2001), Diuridae (2001), Oncidiinae (2001), Pleurothallidinae (2001), Cranichideae (2003), Orchidinae (2003), Cymbidium (2003) and Epidendroideae (2005). A new phylogenetic classification of the whole family was published recently (2003). On the bases of these and other phylogenetic studies, we have turned our attention to evolutionary studies, including pollination biology, origins of polyploids in Dactylorhiza (2001), cytology and genome size (2005) and DNA repair mechanisms. Orchid floral biology has also been re-examined in the light of the phylogenetic studies (2005). The diversity and types of interaction between orchids and their mycorrhizal fungi have been the focus of recent research (2004).
During this period, the first four volumes of Genera Orchidacearum have appeared. The chief editor of this series is Alec Pridgeon, and he is assisted by Phillip Cribb and Mark Chase (both at RBG Kew) and Finn Rasmussen (University of Copenhagen). Contributors to this series have been sought based on expertise and are distributed throughout world, but co-ordination and direction have been supplied by the Kew editors.
Sustainable Utilisation of Plant Resources (2001-2005)
As part of our research on the authentication of extracts from endangered species we have investigated whether some herbal prescriptions contained extracts from orchids. The majority of orchids used in herbal medicines are wild collected and there are conservation issues associated with the over-exploitation of endangered species. Currently, very few of these orchids come from sustainable sources.
The Orchid Specialist Group of IUCN’s Species Survival Commission, which has been chaired from Kew for the past ten years (the previous and current chairs), plays an important role in advising conservation projects, governments and international organisations, such as the CITES Secretariat, on orchid conservation and sustainable utilisation. Its composition is catholic and includes scientists, conservationists and both amateur and professional growers. It runs workshops around the world and has published Orchid Conservation, a book on the latest orchid conservation techniques.
Conservation and Environmental Monitoring (2001-2005)
In the Micropropagation Unit laboratory, orchid seedlings are grown to enhance Kew's living orchid collection, giving priority to increasing the conservation value. Plants in Kew’s collections are pollinated by hand and the seeds stored using methods developed by the Millennium Seed Bank Project (MSBP) (Pritchard and Seaton, 2003). We currently have over 4,000 seed accessions of 1,200 orchid species, from about 270 genera. Many species grown at Kew are not otherwise known in cultivation. In addition to enhancing Kew’s collection, many Madagascan orchid species have been grown from seed for ex situ conservation and repatriation. Many of the methods used are described in Growing Orchids from Seed (2005), which was aimed at conservation groups and growers without access to specialist laboratory facilities.
Since 1983, the Sainsbury Orchid Conservation Project has been growing temperate terrestrial orchids for re-establishment in collaboration with UK conservation agencies. Techniques have been developed for the symbiotic method of germinating seed using mycorrhizal fungi isolated from orchid roots. Trials have taken place on using known fungal isolates from non-orchid sources to stimulate germination (2003). Asymbiotic media and methods have also been developed for species if no effective fungal isolates have been obtained. As well as making these plants more available to the horticultural trade, successes have included the symbiotic propagation and planting of Anacamptis laxiflora (Woods and Ramsay, 2004) and the asymbiotic propagation and re-establishment in the wild of Cypripedium calceolus, used as a case study for orchid conservation worldwide (Ramsay and Dixon, 2003). Successful germination from green capsules can often result in thousands of protocorms being produced, which are excess to requirements. Therefore, cryopreservation techniques are being developed for orchid protocorms of Eulophia epiphytica and Cypripedium calceolus; this allows storage of pre-germinated seed for future use.
Although most orchid micropropagation at Kew is based on in vitro seed germination, some investigations are taking place applying vegetative micropropagation protocols to species such as Erycina pusilla, Erycina pumilio, Leochilus labiatus, Tolumnia variegata and Cypripedium calceolus to provide material and methods for molecular studies. Our approach involves stimulating the formation of protocorm-like bodies (PLBs) from somatic or meristematic regions rather than using protocorms derived from seed (Sarasan et al., in press)
As part of the Conservation Genetics programme, we have carried out population genetic studies on species of Cephalanthera, Cypripedium, Dactylorhiza, Liparis, Neotinea, Orchis and Ophrys, mostly in support of the Species Recovery Programme of English Nature. In addition, we have supervised students from Brazil, Colombia and La Réunion on projects related to orchid conservation.
Extinctions are most frequently asserted after subsequent investigation, so uncertainty often surrounds the classification of a species as extinct. This necessitates acknowledgement of the probabilistic nature of any extinction statement. Exhaustive searches of the known habitats of a species may be impractical as such investigations are often constrained by limited resources. Without extensive fieldwork, the status of a species may only be inferred from sighting records. Several methods have been developed to provide a probabilistic basis for an extinction hypothesis based on such sighting records. It has been suggested that relative levels of threat maybe inferred from the magnitude of the probability generated, with smaller probabilities implying an increased threat of extinction through changes in range and/or abundance. This is potentially of great use because conservationists are often primarily concerned with threatened species rather than those already lost. These methods have been applied to a wide range of taxa, including over 300 species of orchids as there highly co-evolved pollination systems make them idea bioindicators.