| Gouinia polygama E. Fourn., 1885 |
| Gouinia polygama var. major E. Fourn., 1886 |
| Gouinia ramosa Swallen, 1934 |
| Gouinia virgata (J. Presl) Scribn., 1897 |
| Gouinia virgata var. robusta J.J. Ortíz, 1993 |
| Gouinia virgata var. virgata (J. Presl) Scribn., 1897 |
| Gouiniinae P.M. Peterson & Columbus, 2007 |
| Goulardia Husn., 1899 |
| Gouldochloa Valdés-Reyna, Morden & S.L. Hatch, 1986 |
| Gouldochloa curvifolia Valdés-Reyna, Morden & S.L. Hatch, 1986 |
| Gramen Krause, 1914 |
| Gramen Ség., 1754 |
| Gramerium Desv., 1831 |
| Graminastrum E.H.L. Krause, 1914 |
| Graphephorum Desv., 1810 |
| Graphephorum altijugum E. Fourn., 1886 |
| Graphephorum densiflorum E. Fourn., 1877 |
| Greenia Nutt., 1835 |
| Greenia arkansana Nutt., 1835 |
| Griffithsochloa G. J. Pierce, 1978 |