This brassy leggy plant is nothing more nor less than a weed. It is tough as old boots, can read about five feet high if it really wants to, and spreads without mercy. Fortunately it doesn’t seem to set seed, but the roots are just about invincible.
In spring it is a bright green, healthily compact plant, vigorous and cheerful. The leaves smell quite pleasant – a green slightly musty faintly gingery scent. In fact in some places it is called ‘ginger buttons’ and in the 16th century some herbalists were asserting that it was as good as nutmeg and cinnamon. It was extensively eaten in puddings in spring (in fact there was a sort of pudding, something between a pancake and a souffle which was called a tansy) which must have helped against scurvy in the hungry gap. I wouldn’t go that far, but I did make rosemary and tansy biscuits once, and they weren’t bad, in a weird way.
Tansy was used as a strewing herb and a deterrent to flies, and was so valuable that it was taken to New England, where it made itself very much at home. Older herbals recommend it for cleaning wounds, poultices for aching joints, expelling intestinal worms, and disorders from kidney trouble to hysteria (hum). Even then it was meant to be used with caution as in large doses it was found to be an irritant. Nowadays there are NO recommended herbal uses, as it is generally regarded as toxic. One for the history books, I think.