Poison hemlock (conium maculatum) is a flowering plant with fleshy, carrotlike roots that can grow up to ten feet tall. This hemlock is no relation to the coniferous eastern hemlock tree in North America. All parts of the poison hemlock plant contain poison alkaloids. If ingested, conium will cause paralysis of various body systems. Paralysis of the respiratory system is the usual cause of death. Meanwhile, a victim can’t move but is aware of what is happening as the mind is unaffected until death is imminent.

The most famous case of hemlock poisoning was that of Greek philosopher Socrates in 399 BC. The 70-year-old was found guilty of heresy in a trial in Athens. His sentence was death by hemlock, and he had to drink the poison by his own hand. Socrates drank up, then walked around until he noticed his legs were heavy. As shown in this 1787 painting by Jacques-Louis David, Socrates was surrounded by students and adherents as he died.