Puccinia lagenophorae is a gall-causing rust affecting stems and leaves of Common Groundsel (Senecio vulgaris), and occasionally Oxford Ragwort (Senecio squalidus) and Common Ragwort (Jacobaea vulgaris).  It causes swelling and distortion of stems and leaves, with bright orange aecia.  There are no uredinia or spermogonia, and the blackish-brown telia are rarely seen.

There is some disagreement amongst taxonomists as to whether this is a separate species from Puccinia distincta, on Daisy. 

host

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

Groundsel and Ragwort (Senecio and Jacobaea).  In some sources, Daisy (Bellis perennis) is also given as a host; see Puccinia distincta.

Originally of Australian origin, and only known in the UK since 1961. It is now widespread and fairly frequent in Britain. 

There is some disagreement amongst taxonomists as to whether this is a different species to Puccinia distincta, on Daisy. It is given as a separate species in Redfern & Shirley's 'British Plant Galls' and on the 'Plant Parasites in Europe' website.  We are following these two sources and treating them as two species - but as the NBN treats them as synonyms we cannot display a separate distribution map below