Patersonia rudis, commonly known as hairy flag,[2] is a species of plant in the iris family Iridaceae and is endemic to the south-west of Western Australia.

Patersonia rudis is a tufted perennial herb that typically grows to a height of 40 cm (16 in) and forms a rhizome covered by sticky leaf bases.

Flowering occurs from October to December and the fruit is an oval capsule 20–30 mm (0.79–1.18 in) long, containing black seeds.

[6] In 1986, David Alan Cooke and Alex George described two subspecies in the Flora of Australia and the names are accepted by the Australian Plant Census: Subspecies rudis grows in woodland and forest on the Darling Range between New Norcia and Dwellingup in the Jarrah Forest and Swan Coastal Plain biogeographic regions of south-western Western Australia but subspecies velutina grows in more arid woodland and shrubland further east near Southern Cross and Coolgardie in the Avon Wheatbelt and Coolgardie bioregions.

[8][9][11][12] Both subspecies of P. rudis are classified as "not threatened" by the Western Australian Government Department of Biodiversity, Conservation and Attractions.