This paper compiles results of chromosome counts of Paspalum hydrophilum, P. modestum and P. palustre. Four Brazilian accessions of P. modestum have shown 2n = 2x = 20 chromosomes, a number already found in one accession from Argentina and in two from Brazil. Three other Brazilian accessions showed tetraploid level (2n = 4x = 40), which was previously unknown in this species. In P. hydrophilum, only one of the accessions analyzed presented tetraploid level, initially established for the species from plants collected in Argentina. Five additional accessions from Brazil showed the diploid number, previously detected in a single Brazilian population. A tetraploid cytotype was found in P. palustre, previously known as a diploid species. In addition to confirming the occurrence of distinct ploidy levels for all three species, the results establish the predominance of the diploid level in P. hydrophilum and P. modestum accessions collected in Brazil.

Números cromossômicos são relatados para 127 acessos de Paspalum notatum mantidos pela EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária) em coleções de germoplasma em dois centros de pesquisa, no Brasil. A maioria dos acessos foi coletada em seus habitats naturais no Sul do Brasil. O nível tetraplóide (2n = 40) é predominante entre os acessos estudados (91%), confirmando ser esta a situação mais normal para a espécie. Onze acessos com 2n = 20 cromossomos, embora coletados na natureza, provavelmente descendem de populações exóticas da grama Pensacola, comumente cultivadas desde sua introdução no Sul do Brasil, vindas dos Estados Unidos, para cultivo de pastagens permanentes, na década de 60.

Chromosome numbers are reported for 127 germplasm accessions of Paspalum notatum maintained by EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária) in two research centers in Brazil. Most accessions were collected in their natural habitats in Southern Brazil. Tetraploidy (2n = 40 chromosomes) was predominant (91% of the accessions studied), confirming previous reports for the species. Eleven accessions with 2n = 20 chromosomes, although collected in the wild, are possibly derived from 'Pensacola' bahiagrass, commonly cultivated in the area since its introduction from the United States in the 60's, for the establishment of permanent pastures.