It has wrinkled, lance-shaped to egg-shaped leaves with wavy edges, and pink to mauve flowers.

[2][3] Thomasia rugosa was first formally described in 1846 by Nikolai Turczaninow in the Bulletin de la Société Impériale des Naturalistes de Moscou, from specimens collected by James Drummond.

[4][5] The specific epithet (rugosa) means "wrinkled", referring to the leaves.

[3] Wrinkled leaf thomasia grows in heath and mallee shrubland between Lake Grace, Pithara and Donnybrook in the Avon Wheatbelt, Esperance Plains, Jarrah Forest and Mallee bioregions of south-western Western Australia.

[2][3] Thomasia quercifolia is listed as "not threatened" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions.