Please can anyone help by letting me know what this plant is. It suddenly appeared last year, died off in the winter and this year has returned and grown and grown and is now showing yellow flowers at the top part of the plant. Thanks.
It looks like a verbascum to me.
It is called Mullion sometimes grows on the grass verges, the propogated one comes in different colours and is called Verbascome, not sure of spelling.
I think that's the big one, Verbascum bombyciferum
Aarons rod or greater mullein, beautiful just make sure you dead head it as it'll seed everywhere!
Thank you all. I now know it's safe to let it carry on growing.
It's also the food plant of the Mullein moth, so if you find holes appearing in the leaves you'll have brightly coloured caterpillars too!