Taxonomy and distribution of Echinochloa species with special reference to their occurrence as weeds of rice.
About 50 spp. (including subspp. and varieties) of Echinochloa are listed according to their region of origin. E. crus-galli var. bealananensis, E. crus-pavonis var. rostrata and E. zelayensis var. macra have been raised to specific status. Separate tentative keys for the identification of the annual and perennial spp. are given followed by notes on the most widespread spp. and those of greatest significance in rice fields throughout the world. Some taxonomic problems are discussed and lectotypes have been designed for E. glabrescens, panicum crus-galli and P. phyllopogon.