Snap a shot quickly.
When I was over at Keynsham I saw growing alongside but behind a fence in the station two plants of Common Ragwort Senecio jacobaeas AKA Ragweed, St James Wort, Stagger Wort, Stammer Wort, Segrum and in Scotland Stinking Billy.
It is poisonous to horses and consequently there are often campaigns raised against it to root out any found growing where horses and the like could possibly eat it.
I had not got any other lens but the Tamron 18-270 zoom but managed to get a few pictures of it and the leaf shape for my connection.
The larger of the two plants
Of this plant Culpeper the ancient herbalist has to say
Government and virtues: —
Ragwort is under the command of Dame Venus, and cleanses, digests, and discusses. The decoction of the herb is good to wash the mouth or throat that hath ulcers or sores therein: and for swellings, hardness, or imposthumes, for it thoroughly cleanses and heals them; as also the quinsy, and the king's evil. It helps to stays catarrhs, thin rheums, and defluxions from the head into the eyes, nose, or lungs. The juice is found by experience to be singularly good to heal green wounds, and to cleanse and heal all old and filthy ulcers in the privities, and in other parts of the body, as also inward wounds and ulcers; stays the malignity of fretting and running cankers, and hollow fistulas, not suffering them to spread farther. It is also much commended to help aches and pains either in the fleshy part, or in the nerves and sinews, as also the sciatica, or pain of the hips or knuckle-bone, to bathe the places with the decoction of the herb, or to anoint them with an ointment made of the herb bruised and boiled in old hog's suet, with some Mastick and Olibanum in powder added unto it after it is strained forth. In
it Ragweed. Sussex
The second and smaller plant
The unmistakable leaf
It is normally quite easy to spot because the leaf is not similar to many other yellow headed flowering plants.