A taxonomic revision of Trigonostemon (Euphorbiaceae) in Malesia

Trigonostemon is taxonomically revised for Malesia based on herbarium collections and field observations. Thirty-eight species are recognized in Malesia, of which four of uncertain status and four newly described. The previous infrageneric classifications are briefly reviewed, but none is accepted. Some useful characters are discussed. An identification key, nomenclature, descriptions, typification, geographic distributions and taxonomic notes are provided.