| Graphorkis graminea (Lindl.) Kuntze, 1891 |
| Greenwoodia Burns-Bal., 1986 |
| Greenwoodia sawyeri (Standl. & L.O. Williams) Burns-Bal., 1986 |
| Greenwoodiella Salazar, Hern.-López & J. Sharma, 2016 |
| Greenwoodiella deserticola Salazar, Hern.-López & J. Sharma, 2016 |
| Greenwoodiella micrantha (Lex.) Salazar & R. Jiménez, 2016 |
| Greenwoodiella micrantha var. garayana (R. González) Salazar & R. Jiménez, 2016 |
| Greenwoodiella micrantha var. micrantha (Lex.) Salazar & R. Jiménez, 2016 |
| 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 bowringiana (O'Brien) Archila, 2014 |
| 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 |