Single plant growing very close to river in place that often floods.
No interactions present.
I've never heard of Perfoliate Alexanders but looking at images of it I think this is it.
The colour and shape made me think spurge when I saw it and I didn't really think again after that!
Hi, I had never though about it, but now that you say it it's right they look very similar! It may be convergent evolution to attract the same type of pollinators, yellow is for bees, if I remember well!
Lat/Lng: 53.7112, -1.9317
OS grid ref: SE046238
Growing on river side