A taxonomic revision of Cymbopogon (Poaceae) in Thailand

The genus Cymbopogon (Poaceae) in Thailand is revised. Twelve species are recognized, including C. calciphilus, endemic to Thailand. Three species, C. citratus, C. nardus, and C. winterianus, are widely cultivated, considered introduced, and economically important for their aromatic oils, which are used in traditional medicine, perfumery, and other industries; however, there is no evidence that they have become naturalized in the wild. Detailed morphological descriptions, illustrations, and photographs are provided, along with notes on distribution, habitat and ecology, phenology, vernacular names, and uses. Specimens examined are thoroughly documented. Three names are lectotypified in this study: C. cambogiensis, C. khasianus, and C. confertiflorus, which is a synonym of C. nardus. This study provides an updated taxonomic framework for the genus in Thailand and clarifies nomenclatural issues.