Hemlock contains a highly toxic substance which the Ancient Greeks used to put criminals to death. Hemlock (Conium maculatum) is a perennial herbaceous flowering plants in the family Apiaceae. All parts of the plant are toxic. Despite serious safety concerns, hemlock leaves, root, and seeds are used to make medicine. It is used for breathing problems including bronchitis, whooping cough, and asthma; and for painful conditions including teething in children, swollen and painful joints, and cramps. It is also used for anxiety and mania, treatment of spasms tumors, skin infections, epilepsy, Parkinson's disease, Sydenham's chorea, and bladder infections. Illustration by J.J. Grandville.