Puccinia violae is a rust that causes galls on members of the Viola family, including cultivated varieties.  There is no host alternation.  Orange aecia are borne on distorted, swollen areas on the leaves, stems, petioles and sepals.  Uredinia and dark brown telia (non-galling) appear later.  

host

Photograph the rust on the host.  Ensure you have noted the host-plant species in your comments

on Viola species - woodland, parks, gardens