Ptilothrix deusta is a sedge in the family Cyperaceae found in south eastern Australia.

[1] It is commonly seen in wet sandy soils in heathland, growing from 30 to 60 cm tall.

appearing in his Prodromus Florae Novae Hollandiae et Insulae Van Diemen in 1810 as Carpha deusta.

[3][5] The genus name is derived from ancient Greek, meaning feather hair.

The specific epithet deusta is derived from the Latin with a meaning of burnt.