FERNS OF LAOS

There are approximately 215 species of fern in Laos although this is almost certainly an underestimate of the actual number of species due to the extremely low plant collection density for the country (see Newman et al., 2007). However, our list of 215 species already represents a large increase in the number of species listed by Newman et al. (2007) who accounted for about 125 species. Almost all of the species found in Laos are also found in Thailand once the nomenclature as used in Tardieu & Christensen (1939, 1940, 1941) and Newman et al. (2007) is brought up-to-date and synonymy taken into account. The remainder are species found more widely in Asia but missing from Thailand (such as Asplenium prolongatum Hook., Pyrrosia subfurfuracea (Hook.) Ching and Cyclosorus erubescens (Wall. ex Hook.) C.M.Kuo) or species found only in Laos and Vietnam (such as Pteris porphyrophlebia C.Chr. & Ching). One species, Adiantum gingkoides C.Chr., is currently endemic to Laos. Given the large range of topography and habitats in Laos it would be surprising if further collecting did not reveal many more species that are widespread across Asia or species that are known from neighbouring areas of Thailand, China or Vietnam (and Burma where the ferns are even less well known). Further exploration of limestone sites may also uncover locally endemic new species.