Conostylis vaginata is a rhizomatous, tufted, perennial grass-like plant or herb.

[2][3] Conostylis vaginata was first formally described in 1846 by Stephan Endlicher in Lehmann's Plantae Preissianae.

[4][5] The specific epithet (vaginata) means "sheathed", referring to the bracts.

[6] This species of conostylis grows in sand, loam or clay on sand dunes and in winter-wet areas in the Esperance Plains, Jarrah Forest and Mallee bioregions of southern Western Australia.

[3][2] Conostylis vaginata is listed as "not threatened" by the Western Australian Government Department of Biodiversity, Conservation and Attractions.