The Royal Botanic Garden has grown plants originating from the deserts of the since 1683 and we still do today. Currently the support collections, which are used for primarily educational purposes and to supply living material for the rejuvenation of the public displays contain taxa from over twenty countries and four continents.
Many of these plants also have interesting ethno botanical uses or they are under threat in the wild due to habitat destruction and cactus rustling. Others are valued for the diversity of their shape and form, an indication of how they evolved to survive in a difficult climate. Others have adopted interesting pollination strategies with various partners including moths, bats, beetles and humming birds. A visit to the gardens Arid Land House can reveal much of this and provide an insight into these valuable and historic collections, many of which have IUCN status and are protected by CITES.
The collection reflects the work carried out on the Flora of Bhutan and the collections of Paddy Woods in South East Asia. 47% of the material is wild collected. Our collection is important for future research as the plants, in addition to being CITES listed, are becoming virtually uncollectible as permits are increasingly more difficult to arrange and politically volatile areas are becoming more difficult to access.
The South East Asian species have research potential as this region has not been studied in detail and even the hybrids have value. The early hybrids are no longer obtainable and provide an important link back to the story of the orchid obsession. As a whole the collection has a high horticultural research value.
Research is under way at RBGE to establish the phylogenetic history of selected orchid taxa and to understand the processes that led to speciation in the genus Epipactis.
The genus Commidendrum is endemic to the island of St Helena (South Atlantic Ocean) and comprises four species: Commidendrum robustum (Endangered; EN), C. rotundifolium (Extinct in the Wild; EW), C. rugosum (Vulnerable; VU) and C. spurium (Critically Endangered; CR). Although the four species are closely related they show great morphological and ecological variation, representing an example of recent adaptive radiation. As Commidendrum rotundifolium and C. spurium are self-incompatible the accessions held at RBGE are of great conservation value and may be important for species' recovery programmes on St Helena.
The genus Elaphoglossum comprises over 500 species whose distribution includes tropical Africa, South and Central America, Madeira, Tristan da Cunha and St Helena. On St Helena there are four species of Elaphoglossum: the indigenous E. conforme and the three endemic species, E. bifurcatum (Vulnerable), E. nervosum (Endangered) and E. dimorphum (Critically Endangered). The main threats to these threatened ferns include encroachment of habitat from invasive exotic plants.