[Daffynition]

I taken a few *foraging* courses offered by *experts* from the local agricultural colleges. In all cases, the experts who had years and years of experience say...at the end of the course....be *very, very careful* ..if you’re not sure... don’t eat it.

I’m not very confident of what little I know to keep me alive.

[Lurkina.n.Learnin]

You are wise. There is a lot of stuff out there that can be easily confused with deadly consequence. Wild carrot is one . It can be confused with wild hemlock, a real nasty one.

[Dr.Zoidberg]

I'd say these experts are covering their behinds in case someone comes up sick or dead from misadventure, it's the old “Don't try this at home kiddies!” caveat. If you are careful in your identification, and you know what environment to expect to find a particular edible plant, you vastly improve your chances of safe foraging.

As for keeping you alive, exclusively foraging is under the best of circumstances a caloric "break even" proposition, hunter-gatherers were hunters first, because plant nutrition foraged in the wild is a very energy intensive operation usually burning more than it provides in calories to gather the foodstuffs. If you are considering a situation where you might find yourself completely depending on food you can gather by hand, you really have to learn how to hunt, trap and snare both game and fish to supplement your foraging and not be squeamish about where your protein and fats come from.