Water Hemlock Posted on July 20, 2012 by Axie One of North America’s most poisonous plants, contains “cicutoxin.” Many recorded deaths of people, and apparently it kills a lot of grazing livestock. Can grow to 8 feet tall. Apiaceae family. Native. Water Hemlock, Cowbane, Poison Parsnip (Cicuta) Share this: Email a link to a friend (Opens in new window) Email Share on Facebook (Opens in new window) Facebook Print (Opens in new window) Print Share on Pinterest (Opens in new window) Pinterest