Coleosporium tussilaginis s. lat.

Spermagonia and aecia of this rust affect the needles of the alternate host Pine, mainly Pinus sylvestris (Scots Pine).  The species may not be a gall-causer on this host (ref Redfern & Shirley 2023).

Powdery orange uredinia and waxy telia develop on the primary hosts.  This is probably a complex of species and we have treated it in a broad sense, as sensu lato.  Individual species in the complex are described with reference to the primary host; the uredinia and telia of Coleosporium species are indistinguishable morphologically.   Hosts include Tussilago farfara (Coltsfoot), Petasites hybridus (Butterbur), Rhinanthus (Yellow-rattle), Euphrasia (Eyebrights),  Odontites verna (Red Bartsia), Campanula (Bellflowers) and Sonchus (Sow-thistles).   It is a non-galling species on these hosts.  Galls are caused on Jacobaea (Ragwort) - (ref. Redfern & Shirley, 2023)

Puccinia poarum causes galls on Coltsfoot

host

Photograph the rust on the host.  Ensure you have noted the host-plant species in your comments.  

A wide variety of herbaceous species

See species pages on the Fungi of Great Britain and Ireland website and Plant Parasites of Europe (Bladmineerders)

Plant Parasites of Europe includes the following UK species within the complex, depending on the host: Coleosporium campanulae (bellflowers); C doronici (Leopard's-bane); C euphrasiae (Eyebright, Red Bartsia, Lousewort, Yellow Bartsia, Yellow Rattle); C inulae (Elecampane, Ploughman's Spikenard); C melampyri (Cow-wheat); C petasitis (Butterbur, Winter Heliotrope); C senecionis (on Ragworts and some other species in Asteraceae); C sonchi (Nipplewort, Sow-thistles and some other species in Asteraceae);  C tussilaginis (Coltsfoot, and other herbaceous species).  See website for full list.