Microstegium glabratum (Brongn.) A. Camus (Poaceae, Andropogoneae) is a new record for Taiwan, Japan (SW Ryukyus), and China (Hainan). Many specimens have been collected since its first discovery in 1915, but these were misidentified as M. ciliatum (Trin.) A. Camus or M. glaberrimum (Honda) Koidz. Its existence in Taiwan is confirmed by the phylogeny of ITS/5.8S sequences and its identity is figured out after examining the related specimens.