Azalea.

Pretty to look at, but they contain a neurotoxin,  andromedotoxin. Honey produced from the flower is called mad honey and, according to the ancient Roman historian, Pliny the Elder, is said to have been used to defeat an invading army in Turkey. Pliny did not mention if the honey sandwiches were thrown, or offered in a pre battle buffet.
I didn't know about them being poisonous when photographing and eating my honey bakla....
Extra: Iris, which was going to be the main, although I couldn't find any reference to them by Pliny. 

Many thanks to BikerBear for hosting.