The plant taste test is part of the fossilized literature. My personal opinion is there are enough plants out there that will pass this test and then hit you later with some alkoloid compound that is terminal even in ICU. Mushrooms, while delightfull and full of many trace minerals, have very little food value . Sometimes even experts can misidentify a mushroom with lethal results. Chewing on some plant that makes you retch up precious body fluids isn't fun. Food like all other survival efforts must be looked at in terms of gain vs loss. Even a starving predator will pass on prey that fights or flights enough to drain it's energy reserves. Indigenous peoples have very intimate ethno botanical knowledge. You may see them subsist on acorns in the literature, but be assured there were countless other seeds known as emergency resources, if not for a pleasant change in diet. Plant knowledge for a given area holds no real shortcuts. Even in an urban area I see many ethnic groups harvesting an abundance of plants we call weeds. Those overwatered, overfertilised and chemically saturated lawns of golf course and corporate offices are an insult to a marvelous survival plant- the Dandelion.