Once I spoke the language of the flowers...

The Strychnine tree is a deciduous tree native to India and southeast Asia. It is a major source of the highly poisonous alkaloids strychnine and brucine, derived from the seeds inside the tree’s round, green to orange fruit. The seeds contain approximately 1.5% strychnine, and the dried blossoms contain 1.023%. However, the tree’s bark also contains brucine and other poisonous compounds.

Strychnine takes control of the nervous system, flicking on a switch that leads to a flood of painful, unstoppable signals. With nothing to stop the nervous system from firing, every muscle in the body goes into violent spasm, the back arches, breathing becomes impossible, and the victim dies of respiratory failure or sheer exhaustion. Symptoms start within half an hour and death comes a few agonizing hours later. By the end the face of the deceased is fixed in a rigid, terror-stricken grin.  It is rumoured to be the sort of poison that one could develop a gradual tolerance for. The Greek king Mithridates is believed to have slowly built up a resistance to an entire bouquet of poisons, including strychnine, so that he could survive a sneak attack from an enemy. He tested his potions on prisoners before swallowing them himself.

In The Count of Monte Cristo, Alexandre Dumas writes of brucine, another poison found in the seed of the strychnine tree, and suggests that after taking minute amounts and gradually building up a tolerance, “at the end of a month, when drinking water from the same carafe, you would kill the person who drank with you, without your perceiving, otherwise than from slight inconvenience, that there was any poisonous substance mingled with this water.”