| Galphimia glauca | Thryallis glauca | 
| Garcinia madruno | Rheedia madruno | 
| Garcinia magnifolia | Rheedia magnifolia | 
| Gardenia jasminoides | Gardenia grandiflora, Gardenia radicans, Gardenia augusta, Gardenia schlechteri, Gardenia florida | 
| Gardenia taitensis | Gardenia tahitensis, Randia tahitensis | 
| Ginkgo biloba | Ginkgo macrophylla, Salisburia biloba | 
| Gladiolus scullyi | Gladiolus venustus | 
| Glandularia canadensis | Glandularia aubletia, Buchnera canadensis, Verbena canadensis | 
| Gliricidia sepium | Gliricidia maculata | 
| Gloriosa rothschildiana | Gloriosa superba var. rothschildiana | 
| Glycyrrhiza glabra | Glycyrrhiza glandulifera, Glycyrrhiza officinalis, Glycyrrhiza hirsuta, Liquiritia officinalis | 
| Gmelina asiatica | Gmelina parvifolia | 
| Gompholobium confertum | Burtonia conferta | 
| Gonatopus boivinii | Zamioculcas boivinii | 
| Gordonia lasianthus | Gordonia pyramidalis, Hypericum lasianthus | 
| Gossypium hirsutum | Gossypium mexicanum, Gossypium religiosum, Gossypium latifolium, Gossypium taitense, Gossypium punctatum, Gossypium marie-galante | 
| Grahamia coahuilensis | Talinum coahuilense, Talinaria coahuilensis | 
| Grewia avellana | Grewia guazumifolia | 
| Grewia flava | Grewia cana, Grewia hermannioides | 
| Grewia hexamita | Grewia messinica, Grewia schweickerdtii | 
| Grewia monticola | Grewia obliqua | 
| Grewia occidentalis | Grewia chirindae, Grewia microphylla, Grewia rudatisii | 
| Guaiacum angustifolium | Porlieria angustifolia | 
| Guazuma ulmifolia | Guazuma tomentosa, Guazuma polybotrya, Theobroma guazuma, Guazuma bubroma, Theobroma foliis serratis, Diuroglossum rufescens | 
| Gymnocladus dioica | Gymnocladus canadensis | 
| Gynostemma hederifolium | Sicyos hederifolia | 
| Gyrocarpus americanus | Gyrocarpus jacquinii, Gyrocarpus asiaticus |