Water hemlock is considered the most toxic plant in North America. Some sources even consider water hemlock to be the most toxic plant in the Northern Hemisphere. As it turns out, water hemlock is not a single species. Water hemlock represents multiple species that all contain a potent toxin. This toxin disrupts the central nervous system and can lead to death if prompt treatment isn't given. I recently spent some time in the presence of two water hemlock species. If you're interested in learnin