Oleander, Belladonna-Deadly Nightshade, Taxus Baccata, Ligustrum, Poison Ivy (Toxicodendron radicans), Hyacinth, Digitalis purpurea, Angel's Trumpet (Brugmansia)
They all live in our backyards and public parks and potentially are a hugely dangerouus threat to our lives...
http://www.purpleslinky.com/Trivia/Science/Deadliest-Plants-in-the-Planet.145297