They may look harmless enough, but plants can harbor some of the most deadly poisons known. From the death of Socrates by poison hemlock to the accidental ingestion of deadly nightshade by children, poisonous plants have been responsible for human deaths throughout history.

Like pretty well all living things, plants are equipped with natural defense mechanisms that help protect them from all the vicious animals out there that might want to eat them. In addition to stinging spikes and thorns, some plants are filled with deadly toxins that can make us violently ill or even kill us if we unwittingly ingest them. And, depending on where you live, some of these plants might even be growing in your own backyard, so it might be a good idea to learn a little bit more about them.  Get to know some of the most infamous plants and their poisons with this macabre list.