You might've seen news articles about the spread of Poison Hemlock (Conium maculatum) in the U.S. It's a non-native species that's related to carrot and Queen Anne's Lace. Native to Europe and parts of Africa and Asia, it was introduced to America back in the 19th century as an ornamental. It is, however, deadly. (Truth be told, there are a lot of toxic ornamental plants.) Nowadays, it's considered to be a noxious weed.
If you haven't read the news about Poison Hemlock, please do.