There is lots of this growing along the River Cray, so seems to prefer a water location. It has been seen growing up to around 1 metre high with leaves around 40 - 50cms across. I wondered if it was a type of butterbur, but was not sure? Any ideas? Thank you!
yes - you are quite right this is our native Common Butterbur (Petasites hybridus). There are several species of introduced Petasites of which P. japonicus is also this large (or usually bigger still!) - that differs in having less lobed but dentate leaves, creamier flowers and the mature inflorescence is not cylindrical, as here, but hemispherical.
Butterbur is dioecious - i.e. has separate male and female plants - the males are much more frequiently encountered, particularly in southern England and there is some suggestion that the plant may only be truly native where both sexes occur.