This fungal parasite forms a yellow to orange gall, 1–2 cm in diameter, on the underside of leaves of coltsfoot (Tussilago farfara).

[2] On Tussilago farfara (coltsfoot), infection by P. poarum results in large, circular, yellow or orange-red spots that protrude from the undersides of the leaves.

[7] On Tussilago farfara, the rust is necrotrophic, obtaining nutrients from dead cells and plant tissues.

Coleosporium tussilaginis usually appears later in the season and does not form galls or aecia, but instead forms diffuse uredinia with powdery orange spores on the lower leaf surface; it is less obvious on the upper leaf surface,[9] and lacks the purple margin and central hole characteristic of P.

[4] Puccinia poarum completes its life cycle on two different plant hosts: It forms spermagonia and aecia on Tussilago farfara (coltsfoot), and uredinia and telia on the leaves of a grass in the family Poaceae.