>>96029345
Stinging nettles
a relatively normal name but they would drop your IQ a little if you're stung by them, and some int points of it's a enough. They would crop up near societies and pose problems, so people would try to get rid of them after some kids got turned into retards
However, all the intelligence would go into the core of the stinging nettles and form into a shambler, which is just a big plant creature that would be vastly more intelligent than normal people due to amassing intelligence, and would know spells/secrets that a creature of it's expected power really shouldn't and cause major problems