A study has shown that in many cases, “herbal” supplements for “treating” colds and other ailments do not contain the advertised plants, such as echinacea, St. John’s wort, or ginkgo biloba; instead, they contain rice and weeds.
Good luck to all devotees of Ayurveda and dietary supplements.
https://www.nytimes.com/2013/11/05/science/herbal-supplements-are-often-not-what-they-seem.html?ref=science&_r=1
A study using DNA testing offers perhaps the most credible evidence to date of adulteration, contamination and mislabeling in the herbal supplement industry.