A taxonomic study of the genus Pseudoraphis in Thailand was conducted. Four species, P. balansae, P. brunoniana, P. minuta and
P. spinescens are reported. This genus is distributed in the Northern, Eastern, Central, South-Eastern, and Peninsular floristic regions
of Thailand. All the species are aquatic or semi-aquatic, found in swampy places, marshes, lakes, paddy fields, ditches, moats and on
sandy soils from sea level to 300 m. Morphological descriptions, distribution data, and ecological information are provided. All
species are illustrated and a key to the species, based on morphological characters, is provided.
Keywords
Gramineae, grasses, key to the species, revision, taxonomy.