Plant for i.d please

Plant for i.d please

Observation - Plant for i.d please. Description: This plant was growing in and adjacent to a small streamlet running into upper reaches of the Newlands Beck. I can't pin down an i.d - can anyone help please?

This plant was growing in and adjacent to a small streamlet running into upper reaches of the Newlands Beck. I can't pin down an i.d - can anyone help please?