in Sri Lanka - Ministry of Environment

Currently, at a global level, new knowledge in molecular taxonomy has created a vast leap ininformation, leading to dramatic changes in orchid taxonomy and classification. Developmentof the regional botanical surveys in neighboring countries also has led to new knowledge onspecies entities and their distribution patterns. However, at present, the majority of Sri Lankanspecies have not been subjected to such new revisions. Fernando and Ormerod (2008) statedmany such taxonomic discrepancies which need further studies using cross comparativemodern taxonomic revisions along with other congeners.Along with their generic treatments, some of the Sri Lankan taxa have been recently revised,using records and specimens deposited in other herbaria. In most of the recent global revisions,Sri Lankan materials have been omitted due to difficulty of access to specimens. Very fewspecies of Sri Lankan orchids are subjected to modern taxonomic treatments.DistributionThe distribution of family Orchidaceae has mostly correlated with the distribution pattern of themain bioclimatic zones which is governed by the amount and intensity of rainfall and altitude.Dry zone: The recorded lowest number of orchid species (ca15).Vanda tessellata, Vanillawalkeriae and Habenaria plantaginea, have been recorded as the most dominant species.There are no zonal restricted species to this zone.Intermediate zone: This zone lies between the dry and wet zones. The recorded orchid diversityis much higher than the dry zone (ca 28) Oberonia thwaitesii, and Luisia birchea, can beconsidered as restricted to this zone. The eastern part of intermediate zone is associated withthe Savannah grassland vegetation. The species like Rhynchostylis retusa, Aerides ringensand Habenaria roxburghii have been mainly recorded in the eastern part of the intermediatezone among grasslands.Low wet zone: With the aseasonally wet conditions, there is a rich variety of both epiphytesand ground orchids found in this zone (ca 80).Eria articulata, Bromheadia srilankensis, Phaius luridus, Cleisostoma tenuifolium andTaeniophyllum gilimalense are restricted species to low wet zone. The diversity of saprophyticorchids is also high in this zone.Lower mountain zone: This zone represents an altitudinal belt of 900 -1500m between thelow wet zone and montane zone. This area contains the highest orchid diversity with numerousendemics (ca 110) in Sri Lanka. The zonal restricted number of species is also high in this zoneBulbophyllum petiolare, Habenaria pterocarpa and Phreatia jayaweerae are some restrictedmembers to this zone.Montane zone: (ca 55) Area above 1500m has been recognized as this zone. In this zone,orchids are very common but have a lower diversity than the lower montane zone. The coolclimate adapted species are found in this region.Isolated Hills in dry and intermediate zones: These relatively small hills contain a richvariety of orchid diversity (ca 60), a combination of dry zone / intermediate zone species andwet zone species. The lower area of the hill is common with typical dry and intermediate zonespecies, while the hill-top contains mostly wet zone species including many endemics Ritigala,201