Walking over to the bush with the berries, you reach out and are about to pick some off when a light bulb figuratively pops on above your head. Berries, even ones which look appetizing, are not necessarily edible. Pulling backward, you peer at the bush and try to put some taxonomic identification to it. Several seconds of staring manages to stir some recollection in your mind, and the name of the plant leaps out at you as if it were a plant name with springs attached underneath which would enable it to leap in the general direction of people trying to recall it. The vegetation which you were considering for snacking purposes is belladonna, the poisonous plant better known as deadly nightshade! Armed with this knowledge, you stand up and start to move away from the plant. Unfortunately, the common sense which naturally prevents one from consuming unidentified wild flora doesn't help much when you are stuck in the middle of a park and get the munchies, and your stomach growls in protest.