Infects some, but not all, female flowers of sedges including Greater Pond-sedge Carex riparia and Pendulous sedge Carex pendula.  The smut produces masses of olivaceous brown spores within the infloresecence.  Long, pale, straw-coloured elaters project from the female spikes, like small brushes, remaining after the spores have blown away.   The spores are 6-11 µm x 4-6 µm and are finely verruculose.   This is not considered to be a gall-causer; the swelling it causes in the utricles is made of fungal tissue, not host. 

host

Photograph the smut on the host plant, and a close-up of the flowerhead.  In your comments, note the species of sedge affected.  

On flowers of sedges including Carex riparia and C. pendula,  growing on margins of water bodies and woodland for C. pendula. 

June-July.

Rare.  Although its hosts are common, the 2023 record is the only record known for VC55