The fungus Protomyces macrosporus causes galls on stems or leaf of various umbellifers including Ground-elder, Hemlock Water-dropwort, Angelica, Lesser Water-parsnip and Cow Parsley.   The galls are yellow-white irregular swellings.  On some hosts these are sometimes elongated along the veins and midrib, and the leaf-blade may be distorted.  See Redfern and Shirley (2023) for more information on each host.

Other rust galls affecting various umbellifers may be similar, but bear spermogonia, aecia, uredinia or telia - e.g. see Puccinia aegopodii and Puccinia chaerophylli.  

host

Photograph the gall on the host plant.  Ensure you have included a note of the host plant species in your comments 

On umbellifers - roadsides, hedgerows, water's edge etc.

Usually between March and October.

Widespread in Britain.

Status in Leicestershire and Rutland not known.