Also on that list should be all bioengineered (GM) plants. Definitely dangerous and definitely something that shouldn't exist, although they are sadly very common today.
I had a nasty experience with skunk cabbage once. Mistook it for an edible plant when I was just starting out foraging, luckily had the foresight to only eat a little piece but it burned my tongue and mouth for a very long time and was quite painful. Very unpleasant.
I don't want to imagine the consequences had I thrown a pound or two into my juicer and drank it all down, as is my custom with weeds now. :shock: