Megalachne is a genus of Chilean plants in the grass family, found only on the Juan Fernández Islands in the Pacific Ocean, part of the Republic of Chile.

[3][4][5][6] It contains a single species, Megalachne berteroniana.

[7] A genetic analysis found it to be most closely related to the extinct Podophorus, also endemic to the Juan Fernández archipelago.

This clade was in turn found to be nested within a paraphyletic Festuca, most closely related to F. pampeana of South America.

[8] Several species formerly included in genus Megalachne are now considered synonyms of species placed in other genera: This Pooideae article is a stub.