It is a tuft-forming herb with linear to sword-shaped leaves and pale violet tepals.

The flowering scape is 220–500 mm (8.7–19.7 in) long, smooth and softly-hairy near the tip, and the sheath enclosing the flowers is elliptic, 43–68 mm (1.7–2.7 in) long and pale brown.

[2] Patersonia macrantha was first described in 1846 by George Bentham in Flora Australiensis.

[3] Bentham recorded that the type specimens were collected in the Darling Range by Alexander Collie.

[4] However, the sheet bearing the type specimens in the Kew Herbarium was inscribed "Armstrong, Port Essington" in W.J.