It is a tall orchid with a single smooth, tubular leaf and up to thirty or more purplish and white or golden brown and white flowers with a frilled labellum.Prasophyllum sargentii is a terrestrial, perennial, deciduous, herb with an underground tuber and a single smooth green, tube-shaped leaf 150–250 mm (6–10 in) long and 4–10 mm (0.2–0.4 in) in diameter near the base.

The labellum is white, suffused with pink, has frilly edges and is turned upwards towards the lateral sepals.

[3][4][5] The frilled leek orchid was first formally described in 1948 by William Nicholls who gave it the name Prasophyllum australe var.

[4] The frilled leek orchid grows in sandy soil in shrubland and woodland, usually flowering after fire or light disturbance.

[4][3][7] Prasophyllum sargentii is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.