It has a single tubular leaf and up to thirty five scented, brown or reddish-brown flowers with a pink or purplish labellum.

Richard Sanders Rogers, who named this species, described the flowers as "prune-coloured".

[3] Prasophyllum constrictum was first formally described in 1909 by Richard Sanders Rogers from a specimen collected near Tailem Bend and the description was published in Transactions, proceedings and report, Royal Society of South Australia.

[4] The tawny leek orchid grows in shrubby forest mainly in the Adelaide Hills and Mount Lofty Ranges.

[3] Prasophyllum constrictum is listed as "Rare" under the South Australian National Parks and Wildlife Act 1972.