Chelidonium majus Greater Celandine C DD N?
This possibly native, hedgerow plant is a member of the Papaveraceae (Poppy family) and not Ranunculaceae (Buttercup family) so the English name leads to confusion as Greater and Lesser Celandine are not near relatives. The leaves are what I look out for being light green almost glaucous often hiding not very significant yellow flowers. It starts to bloom just as the Lesser Celandine is finishing so it is a rare year when both these plants, which grow on the verges near where I live, are in flower simultaneously. A good distinguishing feature of this plant is its sap which is bright orange and used to be thought good for curing warts.
Chelidonium majus is found abundantly in England and Wales but records diminish as you go past the Scottish border and there is little near the north coast. In Ireland it is found mostly towards the north east.