Atropa belladonna

Atropa belladonna, also known as Deadly Nightshade, was a plant native to Earth which contained the poison atropine. Belladonna was used to poison the water supply of the Sense Sphere by crazed humans when the First Doctor, Ian Chesterton and Barbara Wright arrived in the 28th century. This was the only water available to the TARDIS crew during their stay. (TV: The Sensorites)