Puccinia caricina

A brown rust affecting Carex pendula.

Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features then in the comments box describe the size and identifying characters you have observed.

Grows on on live leaves of Carex pendula.

When Carex pendula is in leaf.

A common rust on Carex pendula but  rarely found on the alternate host (Ribes species)

Widespread and fairly frequent in Britain.

Not often recorded  in Leicestershire and Rutland, possibly due to the difficulty of identification.