Can cause cirrhosis of the liver, and is particularly dangerous to horses, pigs and cattle.
Yew: Toxic leaves can cause convulsions, breathing issues and heart failure, especially in horses, cattle, and pigs.
Foxgloves (digitalis): Overdose causes nausea, vomiting and diarrhoea, and in extreme cases death. Toxic to poultry, cattle, cats and dogs.
Sycamore seeds: Cause 'equine atypical myopathy', which weakens horse muscles so they struggle to breathe and then die from cardiac arrest.
Hemlock water dropwort (poison parsnip): Possibly the deadliest indigenous plant in Britain. Used in ancient Europe to execute people.