A rust on the leaves of Hawksbeards, Crepis.  There is no host-plant alternation, and only uredinia and telia are formed.  These can be on both sides of the leaves, and are small and brown.  The urediniospores have 2 or 3 pores.  The teliospores are two-celled, with very short pedicels.

host

Photograph the rust on the host plant, on both sides of leaf; ensure you have identified the host and have included a note of the host plant species in your comments.  For certain identification we recommend that the spores are examined microscopically.

on hawksbeards; path edges, roadside verges, rough grassland, waste ground, etc.