One of the most poisonous of garden plants in the world, oleander can send you into cardiac arrest within minutes of ingesting it. All of the plants parts are toxic; the leaves, flowers and fruit contain cardiac glycosides, which have therapeutic applications but are toxic if eaten in the wrong measure. Surprisingly for such a poisonous plant, there have only been 3 deaths in the Unites States in the 20-year period from 1985-2005.