Gastridium phleoides (Nees & Meyen) C.E. Hubb.
Gigantochloa albociliata – synonym of Pseudoxytenanthera albociliata
Gigantochloa heterostachya – synonym of Bambusa heterostachya
Glyceria pilosa Steud. – synonym of Eragrostis japonica (Thunb.) Trin.
Guadua angustifolia Kunth ssp. chacoensis – synonym of Guadua chocoensis
Guaduella ledermannii Pilg. – synonym of Guaduella densiflora Pilg.
Guaduella longifolia Camus – synonym of Guaduella marantifolia Franch.
Guaduella macrostachys (K.Schum.) Pilg.
Guaduella marantifolia Franch.
Guaduella marantifolia var. duparquetii Franch. – synonym of Guaduella marantifolia Franch.
Guaduella mildbreadii Pilg. – synonym of Guaduella marantifolia Franch.
Guaduella oblonga Hutch. ex Clayton
Gymnothrix uniseta – synonym of Pennisetum unisetum