Nordic Journal of Botany 26: 257Á316, 2008 doi: 10.1111/j.1756-1051.2008.00265.x, # 2008 The Authors. Journal compilation # Nordic Journal of Botany 2008 Subject Editor: Henrik Ærenlund Pedersen. Accepted 13 October 2008 An annotated checklist of the Orchidaceae of Laos Andre´ Schuiteman, Pierre Bonnet, Bouakhaykhone Svengsuksa and Daniel Barthe´le´my A. Schuiteman ([email protected]), Nationaal Herbarium Nederland, Univ. Leiden, PO Box 9514, NLÁ2300 RA Leiden, the Netherlands. Á P. Bonnet, CIRAD and UM2, UMR AMAP, FRÁ34000 Montpellier, France. Á B. Svengsuksa, National Univ. of Lao PDR, Faculty of Science, Dept of Biologie, PO Box 7322, Vientiane, Laos PDR. Á D. Barthe´le´my, INRA, UMR AMAP, FRÁ34000 Montpellier, France. A checklist is presented of the orchid flora of Laos, enumerating 485 species in 108 genera. An estimate is given of the expected size of the orchid flora of Laos. Notes on habitat, global and local distribution, endemism, conservation, phenology, as well as a systematic overview complement the checklist. Origin of the checklist Á The karst formations and montane forests in the Lak Xao district, Bolikhamxai province. The checklist presented below grew out of a UNESCO Á Various sites in the Phou Khao Khouay NBCA, project (reference no. 27213102 LAO) and the ORCHIS Vientiane and Bolikhamxai provinces. project (Bhttp://www.orchisasia.org/). The first, entitled Á The Phou Phanang NBCA, Vientiane prefecture. ‘Systematic study of the wild orchids in Lao P.D.R. and Á The Louangphrabang district, Louangphrabang pro- their conservation’, was conducted during the year 2005 by vince. Bouakhaykhone Svengsuksa. Some 700 living orchid speci- Á The Oudomxai district, Oudomxai province. mens, collected in various localities in Laos, formed the Á The Nam Ha NBCA and the districts of Xieng Kok basis for the first orchid collection at the National and Muang Sing, Louang Namtha province. University of Laos (NUOL) in Vientiane. The ORCHIS Á The districts of Ou Tai and Phongsali and the Phou project, which was carried out during the years 2006Á2008 Den Dinh NBCA, Phongsali province. (Acknowledgements), had the objective to develop an identification tool for a significant part of the orchid flora Field trips by staff members of the National University of of Laos. Among the main goals was to facilitate monitoring Laos, as well as specimens assembled during the Darwin and regulating the trade in these plants. To achieve these project directed by Dr M. Newman and during the Biotik aims it was mandatory to get a better insight into the project directed by Dr P. Grard, also enriched the living distribution and ecology of orchids in Laos. During thirty collection. field trips about 1400 carefully selected living plants were As a result of these collecting activities, much of it collected, which were subsequently cultivated in the green- performed in areas never visited by botanists before, about houses at NUOL. In this way species that were not 145 species and 19 genera of Orchidaceae could be added to encountered during anthesis could be studied and identified the orchid flora of Laos as described by Seidenfaden (1992). as they flowered in cultivation. In addition, for many species already known from Laos new The following localities have been visited in the course of provincial records could be established. the ORCHIS project: An unfortunate omission in Seidenfaden’s otherwise admirable publication is the complete lack of information Á The tropical lowland forest of the Xe Pian NBCA on such data as habitat, altitude and phenology. Where this (National Biodiversity Conservation Area), Champa- information was available it is incorporated in the present sak province. checklist. For many species, however, even the most basic Á Various localities on the margin of the Bolovens ecological data are still wanting. plateau, Champasak and Attapu provinces. Work on our checklist commenced while the Darwin Á The Dong Ampham NBCA, Attapu province. project, which resulted in a checklist of the vascular plant Á The karst formations of the Phou Hin Boun NBCA, flora of Laos (Newman et al. 2007), was nearing its Khammouan province. completion. A preliminary version of our checklist was Á The Nakai plateau in the Nakai-Nam Theun NBCA, published on the internet. This was (and at the time of Khammouan province. writing still is) regularly updated as new species records 257 came to light. With our consent this preliminary list (in its An alternative way to estimate the orchid diversity of February 2007 state) was incorporated in Newman et al. Laos is to take the number of species currently recorded (2007). However, since that time many more orchid species (485 according to our checklist) and to add the number of have been identified as new for Laos. Moreover, our data on species that may be expected to occur in Laos based on an collections, distribution, ecology and phenology were not analysis of distributional and ecological data. In this way we included in Newman et al. (2007). This, in our opinion, arrive at an estimate of 831 species. Since these two justifies the publication of the present checklist, even estimates are very similar they may contain more than a though many of our results were inevitably anticipated grain of truth, even though they are not completely in Newman et al. (2007). Since the section on Orchidaceae independent. in the latter is not only based on our preliminary list but on Another indication that our current checklist is still far other sources as well it contains a number of additional from complete is the fact that for several provinces there are species and province records. We have collected in the last hardly any records at all (see Local distribution). It is also part of this paper those species records which in our opinion worth pointing out that Laos contains the largest part of the require confirmation (see List of synonyms and question- central Indochina limestone belt (Rundel 1999). Schmid able records in Newman et al. 2007). There we also list a (1974) suggests that this area is rich in endemic species, but number of cases where our views on nomenclature and poorly known at present. Furthermore, this habitat type is synonymy are at variance. already recognized in the neighbouring countries as being a The aim of our checklist is thus to present an overview of particularly rich one (Shui and Chen 2006), especially in all orchid species currently recorded from Laos, combining orchids (Averyanov et al. 2003). Many new records in our results from the ORCHIS project and previous studies, checklist, for example of rare species like Eparmatostigma including information on species distribution, habitat and dives (Rchb. f.) Garay (Schuiteman and Bonnet 2008) and phenology. Apart from the obvious functions that such a Thaia saprophytica Seidenf. (Schuiteman et al. in press), are checklist fulfils we consider the fact that our work clearly due to field trips conducted at the margin of this largely outlines the still considerable gaps in our knowledge unexplored and almost impenetrable area. another useful property. We hope it will stimulate scientific It may be of interest to note that the following genera, exploration and botanical research in Laos. according to our analyses, are expected to occur in Laos, although they are absent from the checklist: Acanthephip- pium, Adenoncos, Amitostigma, Armodorum (but see List of Estimated size of the Lao orchid flora synonyms and questionable records in Newman et al. 2007), Cremastra, Cryptochilus, Cryptostylis, Didymoplex- The flora of Laos has so far received much less attention iella, Didymoplexiopsis, Didymoplexis, Diglyphosa, Diplo- from botanists than some of the neighbouring countries, meris, Dipodium, Eriodes, Erythrodes, Galeola, Grosourdya, such as Thailand or Vietnam (Newman et al. 2007). As a Hemipilia, Herminium, Herpysma, Lecanorchis, Ludisia, result, the orchid flora in particular is still very poorly Macropodanthus, Microsaccus, Neuwiedia, Phreatia, Pla- known (Schuiteman and de Vogel 2000). The most recent tanthera, Rhomboda, Stereochilus (recently one as yet critical overview of the orchid flora of Laos is contained in a unidentified and possibly undescribed species from Laos major work on the Orchidaceae of Indochina (Seidenfaden came to our notice; see Endemism), Stereosandra, Thecopus, 1992). In that publication 335 species of Orchidaceae are Tuberolabium, Vrydagzynea, and Yoania. recorded from Laos. Even if we take into account the smaller surface area of Laos compared to Thailand and Vietnam it is obvious that this figure must be a gross Local distribution underestimate of the actual number of orchid species occurring naturally in this country (Table 1, based on At the province level it becomes even more apparent that figures from Schuiteman and de Vogel 2000 and Averyanov Laos is still severely underexplored botanically. Our find- 2003). ings confirm the pattern shown by Newman et al. (2007), Assuming that the orchid diversity of Laos is comparable who demonstrated that for some provinces there are hardly to that of Vietnam (in terms of number of species per any floristic data available. Especially the four northern 100 km2) and taking into account that according to provinces (Bokeo, Louang Namtha, Oudomxai and Phong- Averyanov (2003) at most 80% of the species of that sali) are very poorly represented in their checklist of the country have been recorded, we can deduce from this table vascular plants of Laos, while the same applies to Xekong in that the actual number of orchid species in Laos should be the south and to the central province of Xaisomboun. This close to 800. is of course a mere artifact of collecting and in no way reflects a lower diversity of these ‘neglected’ provinces. The validity of this statement is easily demonstrated by the fact that during a few short excursions to the Phongsali Province Table 1. Comparison between the Orchid flora of Laos, as presently the present authors and their co-workers were able to record known, and that of neighbouring countries.