And before anyone makes a cheeky “what do you need this for 🤨” comment, I’m a writer. I’m not going to murder anyone I promise, I just want to write a scene where one guy gets poisoned.

I need something that doesn’t require modern technology to extract/produce, and would make sense to be avaible in a place with a temperate to mediterranean climate. The slower, the better. Does a plant or something like that exist or do I need to make one up?