| Genea tetorum (L.) Dumort., 1868 |
| Geopogon Steud., 1840 |
| Germainiinae Clayton, 1972 |
| Gigachilon Seidl, 1836 |
| Gigantochloa Kurz ex Munro, 1868 |
| Gigantochloa aspera (Schult. & Schult. f.) Kurz, 1876 |
| Gigantochloa levis (Blanco) Merr., 1916 |
| Gimnatereas É. Desv., 1854 |
| Ginannia Bubani, 1901 |
| Ginannia lanata (L.) F.T. Hubb., 1916 |
| Ginannia pubescens Bubani, 1901 |
| Glandiloba (Raf.) Steud., 1840 |
| Glutinosa Zuloaga, 1978 |
| Glyceria R. Br., 1810 |
| Glyceria borealis (Nash) Batch., 1900 |
| Glyceria brevifolia (Muhl.) Schult., 1824 |
| Glyceria elata (Nash) M.E. Jones, 1910 |
| Glyceria fluitans (L.) R. Br., 1810 |
| Glyceria fluitans var. acutiflora Döll, 1855 |
| Glyceria fluitans var. angustata Vasey ex Fernald, 1895 |