Plant growing on wall

Plant growing on wall

Observation - Plant growing on wall - UK and Ireland. Description: I can't find this in my flower book, it had a bumblebee (B. pratorum worker) feeding on it - the first I've noticed on this species of plant.

I can't find this in my flower book, it had a bumblebee (B. pratorum worker) feeding on it - the first I've noticed on this species of plant.