5) English yew (Taxus baccata)

Fittingly, this plant is often found in graveyards. It’s thought that it had some kind of spiritual meaning to medieval Englishmen. Pretty much the entire tree is poisonous and the level of potency rises as it dries out. The poison is called taxine and horses are particularly sensitive to it. The main symptoms are increased heart rate, muscle tremors, convulsions, collapse, difficulty breathing, circulation impairment and eventually heart failure. Terrifyingly there are sometimes no symptoms at all and the poor victim just drops dead after a few hours.

So there’s five plants to avoid if you’ve got any sense. Or to put it another way, there’s five plants to seek out if you’re feeling either suicidal or murderous.