The fungus Microbotryum parlatorei affects Rumex species causing galls in stems, petioles and midribs, often with distortion and swelling of infected parts, which eventually rupture revealing the dark-violet dusty spore-mass.

host

Unless identified by a recognised expert, photos are required, showing the smut and the host.  Ensure you have included a note identifying the host-plant

Rarely recorded in Britain.

Rare in Leicestershire and Rutland.