Really only associated with Groundsel and Oxford Ragwort.
Clearly a puccinia rust.
Photos show Common Groundsel (Senecio vulgaris) UK
• https://www.naturespot.org.uk/species/puccinia-lagenophorae
♦ http://www.dorsetnature.co.uk/pages-fungi/f-83.html
• https://eol.org/pages/16336