Lyperanthus serratus, commonly called rattle beaks, is a species of orchid that is endemic to the south-west of Western Australia.

[4][5] A powdery bloom covers the entire plant, except for the innermost parts of the flower.

The single leaf is lance-shaped, 150–350 cm (60–100 in) long and 10–15 mm (0.4–0.6 in) wide, dark green with a paler lower surface.

The specific epithet (serratus) refers to the white calli found on the labellum, appearing like serrations on its edge.

[8][9] The species occurs in the Avon Wheatbelt, Esperance Plains, Jarrah Forest, Swan Coastal Plain and Warren biogeographical regions of Western Australia on sand, loam or sandy clay.