Wildcrafting—harvesting plants from the wild—is something we've been doing since long before we became human. For many millions of years, we've been eating wild plants. And we've been using plants medicinally for at least several million years, judging by the fact that some of our fellow apes have been observed using medicinal plants in the wild. In so-called "hunter-gatherer" societies, it is plants that make up the bulk of their food source, not meat as the stereotypes insist, so they really ought to be called "gatherer-hunters." Gathering wild plants has been imperitive to our survival throughout history (and "pre-history"), even in agricultural societies, which continue to gather plants for medicine, or for food when planted crops fail.

In modern times, the human population is much too large to be supported by wild foods. Overharvest has already severely affected some wild medicinal plants, such as ginseng. But limited wild harvesting is possible, if you're careful not to overharvest, and to remember the needs of other harvesters (both human and animal) and the plant's own needs for survival and reproduction.

Before you harvest a plant, make sure you have it properly identified. (A field guide such as Newcomb's or Peterson's is helpful, or something more technical like Gray's Botany if you're up for it.) If you misidentify a plant, you may harvest an endangered species, or possibly something poisonous.

Make sure the species you're harvesting isn't an endangered, threatened, or rare plant. Most likely such plants are under stress from habitat loss, development, or encroachment by invasive species; don't add to this by harvesting, even if it seems locally abundant: it may be severely endangered on a landscape scale. Check with your state (or province or whatever) natural resources department for a list of these plants. Many states and counties have this list online.

Once you've established the plant isn't rare, make sure there are many in the area. You don't want to harvest the only individual within the area, even if it is common elsewhere. If you can, find a large stand and harvest as little from each plant as possible. This reduces your impact, both on the individual plant and on the stand as a whole. Don't harvest a plant unless you have a good reason: food, medicine, etc. Don't just harvest because you can; harvest when you have a legitimate use planned for that plant. Killing a plant needlessly is disrespectful, unethical, and potentially harmful ecologically, even if it is a common species.

In cultures such as the Native Americans who rely on wild plants for food, medicine, and ritual purposes, there are complex sets of rules about harvesting wild plants. These rules exist to prevent overharvest and to foster respect for plants, which is necessary in societies which rely on wild food sources. Many tribes leave an offering of tobacco or other sacred herb at the base of the plant, and most say a prayer of thanks to the plant or the Creator/Great Spirit. I always thank a plant when I harvest it, to show that I respect it and appreciate its sacrifice. This isn't necessary, of course, but I think it helps to remind us that the other living things around us are not just inanimate objects, they are fellow members of the community of life, living beings who, though they may not be "conscious" in the human sense, have needs and have the inherent right to not be used without reason. This isn't about being an environmental saint, it's about survival. We need to respect other living things if we want to continue to exist.