Hemlock
From Tardis Wiki, the free Doctor Who reference
Hemlock was a plant with poison-tipped thorns.
In 12th century England, hemlock was used in certain quantities as a medicine for pain relief. (AUDIO: Abbey of Heretics)
Its modification was used as ammunition in Grave Diggers weapons. (PROSE: The Secret in Vault 13)
Calidora committed suicide using hemlock. (COMIC: The Chains of Olympus)