The Brazilian bamboo genus Eremocaulon is revised, including a key to its five species, descriptions, illustrations, and a distribution map. Our modified circumscription of Eremocaulon unites E. aureofimbriatum with four other species based on a unique combination of both vegetative and reproductive characters, including leathery culm leaves bearing oral setae, an elongated, persistent prophyll at the base of the primary branch, pseudospikelets, and six stamens. The western Amazonian species E. amazonicum, with capitate clusters of pseudospikelets, is newly described, as is E. setosum from the Atlantic forests of São Paulo. The monotypic genus Criciuma is recognized as a synonym of Eremocaulon, resulting in the new combination E. asymmetricum, and Guadua capitata is transferred to Eremocaulon as E. capitatum. Apoclada, Eremocaulon, Guadua, Olmeca, and Otatea, the five currently recognized genera of the Guaduinae, are compared and contrasted.

Communicating Editor: Paul Wilson