hin[22] - Milk Parsley

Milk Parsley in flower.
Selinum palustre is a previous name for this plant.
en.wikipedia.org/wiki/Peucedanum_palustre

This plant needs to be encouraged - it is the primary [if not sole] food plant for the caterpillars of the very rare Swallowtail butterfly. [currently, it confined to areas of the Norfolk Broads - and despite looking, I didn't see one].
en.wikipedia.org/wiki/Papilio_machaon