Hey, how are you? Haven't been around for too long... just stumbled across this post, as it reminded me of a similar plant that grows in our area, particularly around rivers and creeks.
Our parents always told us, to never put any plants in our mouth, as this one, although most likely the most dangerous, was not the only one that could harm a child.
Wasn't Sokrates killed by that too?
RE: UK's Most Deadly Plant by the River Teme - Ludlow, Shropshire