A garden featuring intoxicating and poisonous plants was added in February 2005. Species of the Poison Garden include Strychnos nux-vomica (source of strychnine), hemlock, Ricinus communis (source of harmless castor oil but also deadly ricin), foxglove, Atropa belladonna, Brugmansia and Laburnum. The mission of the Poison Garden also includes drug education, with featured plantings of cannabis, coca and the opium poppy Papaver somniferum.