Oleander (Nerium oleander)
Why we grow it: Its fragrant white buds and thick, dark green leaves make it a popular ornamental shrub for gardens across the country.
Deadly parts: The entire plant, including its nectar and sap
Toxic toll: Think twice about growing one of these babies in your yard, especially if you have little ones: a single leaf contains enough toxins to be lethal to an infant or small child. Like other poisonous plans, ingesting it first affects the digestive system with vomiting and diarrhea, then poisoning progresses into life-threatening circulatory problems. If your heart's still ticking after that trauma, oleander can also deal a fatal blow to your central nervous system, causing seizures, tremors, and coma that can lead to death.