Sometimes, wild food sources can be scarce. Especially during the winter months. But did you know that many kinds of trees contain an emergency food source, which can be accessed all year round? Certain trees contain an edible inner bark, known as cambium. The cambium layer in edible trees contains loads of starches, minerals, vitamins, and some sugars. Knowing which trees to harvest from, and how to harvest them could save your life one day. However, cambium is known as an emergency food. That means it should not be harvested under normal circumstances, because doing so can cause severe damage to the tree. By far, the most popular tree for harvesting cambium from is the pine. Most pine species contain edible cambium, although not all. This is why it's good to thoroughly research the trees in your area so that you can become familiar with the edible species, and also the ones that aren't good to eat from.