Medicinal herbs should be:
1) Gathered in the proper season.
General rules are:
Barks in the spring;
leaves before the plant flowers;
flowers on the first day of opening;
roots are best in the fall (although they are sometimes harvested in spring, previous to aerial plant development).
2) Gathered in wild habitats where the plants naturally grow or should be organically grown according to certification standards established by the state in which they were harvested.
3) Harvested in an area free of chemical/industrial pollution of air, water and soil.
4) Gathered at least 1/4 mile from any traveled roads, and at least 10 miles from any waste disposal or toxic dumping areas.
5) Protected from over-harvesting by leaving at least 3/4 of the stand intact for reproduction and continuance of the species. If roots are dug, root crowns and seeds must be replanted to perpetuate the growth and proliferation of the plant.