A rust fungus that causes galls on the stems or leaves of Salad Burnet (Sanguisorba minor).  There is no host-plant alternation.  The aecia are orange, and on both sides of the leaf; later on, yellow uredinia and black telia are present on leaf undersides. 

host

Photograph the rust on the host, on both sides of leaf.  Ensure you have noted the host-plant species in your comments

on Salad Burnet