Oryza grandiglumis is a type of wild rice of the genus Oryza found in tropical countries of South- and Central- America, namely Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Paraguay, Venezuela, and Peru. Studied in 1998 in Caño Negro, in northern Costa Rica, it is an annual plant with short rhizomes; its culms can reach and are in thickness. They have developed aerenchyma which allows them to float.
Oryza grandiglumis is a tetraploid of 2n=48. It has a genome as with several others in the O. officinalis complex.