| Greenwoodiella wercklei (Schltr.) Salazar & R. Jiménez, 2016 |
| Guarianthe Dressler & W.E. Higgins, 2003 |
| Guarianthe aurantiaca (Bateman ex Lindl.) Dressler & W.E. Higgins, 2003 |
| Guarianthe bowringiana (O'Brien) Dressler & W.E. Higgins, 2003 |
| Guarianthe skinneri (Bateman) Dressler & W.E. Higgins, 2003 |
| Guarianthe x guatemalensis (T. Moore) W.E. Higgins, 2004 |
| Guarianthe x laelioides (Lem.) Van den Berg, 2015 |
| Gularia Garay, 1982 |
| Gularia crenulata (L.O. Williams) Garay, 1982 |
| Gularia trilineata (Lindl.) Garay, 1982 |
| Gymnadenia R. Br., 1813 |
| Gymnadenia propinqua A. Rich. & Galeotti, 1845 |
| Gyrostachys Pers. ex Blume, 1859 |
| Gyrostachys aguacatensis (Rchb. f.) Kuntze, 1891 |
| Gyrostachys aphylla (Hook.) Kuntze, 1891 |
| Gyrostachys apiculata (Lindl.) Kuntze, 1891 |
| Gyrostachys aurantiaca (Hemsl.) Kuntze, 1891 |
| Gyrostachys chloreaeformis (A. Rich. & Galeotti) Kuntze, 1891 |
| Gyrostachys cinnabarina (Lex.) Kuntze, 1891 |
| Gyrostachys comosa (Rchb. f.) Kuntze, 1891 |