What is the world's most poisonous flower?

The most poisonous plant is the oleander, or Nerium oleander, which is a beautiful flowering shrub that contains poison in every part, according to How Stuff Works. Swallowing oleander can cause intense stomach pain, vomiting, diarrhea, irregular heartbeat and death.

How Stuff Works explains that eating a single leaf of the oleander plant can kill a child and that even honey made by bees that have ingested oleander nectar can poison a person. The flowers on this shrub are beautiful and fragrant, growing in a variety of colors while the shrub itself can reach up to 20 feet tall and 12 feet wide, according to the National Gardening Association website.