Mycology

Who ever wrote that is probably dead by now.

Deadly Galerina likes to grow on dead conifers.

Death Cap grows on tree roots, not sure if that counts.

There aren’t a ton of mushrooms that grow on healthy living trees I think, so it’s kinda hard to find a poisonous example but maybe Jack O’ Lanterns count. They can grow at the base of living hardwood trees. They won’t kill you but you will have a very bad time. I think there’s another closely related species that grows on both conifers and hardwoods.