TAXONOMIC REVISION OF THE GENUS Cymbidium Sw. (ORCHIDACEAE) IN NEPAL

Abstract

Cymbidium is the epiphytic, terrestrial, lithophytic orchid with a distinguishing character of linear to elliptic-lanceolate leaves, 2 or 4 pollinia in 2 unequal pairs, and the genus mostly occur on the tree trunks covered by mosses. This study is based on all the species of the taxa that are naturally distributed in Nepal. This taxonomic revisionary study is based on the herbarium specimen and fresh plant materials. The herbarium specimens are thoroughly studied from KATH and TUCH and the examination of available images of herbarium specimens collected from Nepal are also done in international herbaria like BM, CAL, E, K and TI. This study confirms the presence of 10 species of Cymbidium in Nepal namely; C. aloifolium, C. crassifolium, C. cyperifolium, C. devonianum, C. elegans, C. erythraeum, C. × gammieanum, C. hookerianum, C. iridioides and C. lancifolium. The synonyms, type specimens, description, ecology, altitudinal range, flowering season, specimen examined and distribution map for all the species present in Nepal is prepared. Also, the illustration and bracketed taxonomic key is made to identify the species. The character of lip is more important in taxonomic view point for delimiting the species of this genus. Micromorphological character like the stomata complex in 10 species of Cymbidium were studied for understanding the taxonomic significance of stomatal complex within the genus. Stomatal index and stomatal frequency were calculated using formula given by Salisbury. Paracytic type of stomata were found in the species that are either arranged in linear form or scattered. The elliptical shape of stomata was found in more species than the circular shape. Furthermore, the cladistic analysis is also interpreted to find out the phylogenetic relationship among the species. The cladogram showed that C. aloifolium and C. crassifolium are closely related. The genus Cymbidium is found to be distributed in all 3 regions of Nepal with the altitudinal range from 800 – 2800 m in 23 districts of Nepal. The flowering period of the genus Cymbidium is usually throughout the year as several species bloom in different season.