|Poison Hemlock (along a local hiking trail)|
You need to know what dangerous look-a-likes may exist (queen anne's lace or poison hemlock?). Also, how to avoid dangerous situations (don't plant deadly monkshood next to your edible chicory). You need to know that some plants have edible parts and toxic other parts. And still others need to be harvested at specific times or need special processing to make them usable and non-toxic.
Knowledge is power. Certainly so in this case. But even more than power, this knowledge teaches you to respect the power our green friends have. They can cure us or kill us with equal ease.
(If you like this sort of info, be sure to catch my daily herb posts at the Classical Formulas Facebook page.)