Hemp Agrimony (Eupatorium cannabinum). Widespread plant of marshy margins, ditches, damp grassland and riverbanks. Seen here at Burymead Springs in Hertfordshire. 

 The area is described in local literature as "part of an ancient riverside meadow, sandwiched between the River Hiz, the Hitchin railway flyover and a scrapyard". Nonetheless nature continues to thrive in this fragment of an older landscape.