| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Urtica dioica | Flower | -- | -- | * | |
| Hibiscus sabdariffa | Root Bark | -- | -- | * | |
| Pimpinella anisum | Seed | -- | -- | Williamson, E. M. and Evans, F. J., Potter's New Cyclopaedia of Botanical Drugs and Preparations, Revised Ed., Saffron Walden, the C. W. Daniel Co., Ltd., Essex UK, 362 pp, 1988, reprint 1989. | |
| Avena sativa | Sprout Seedling | -- | -- | * | |
| Prunus serotina | Bark | -- | -- | * | |
| Artemisia vulgaris | Plant | -- | -- | Bisset, N.G., ed. 1994. Herbal Drugs and Phytopharmaceuticals. CRC Press. Boca Raton, FL. 566 pp. | |
| Polygonum multiflorum | Plant | -- | -- | * | |
| Artemisia annua | Plant | -- | -- | * | |
| Withania somnifera | Plant | -- | -- | ANON. 1948-1976. The Wealth of India raw materials. Publications and Information Directorate, CSIR, New Delhi. 11 volumes. | |
| Ipomoea purga | Tuber | -- | -- | * | |
| Azadirachta indica | Plant | -- | -- | * | |
| Taraxacum officinale | Flower | -- | -- | * | |
| Zizyphus jujuba | Plant | -- | -- | * | |
| Centaurea cyanus | Shoot | -- | -- | Jim Duke's personal files. | |
| Datura innoxia | Plant | -- | -- | * | |
| Artemisia dracunculus | Shoot | -- | -- | * | |
| Menyanthes trifoliata | Shoot | -- | -- | Bisset, N.G., ed. 1994. Herbal Drugs and Phytopharmaceuticals. CRC Press. Boca Raton, FL. 566 pp. | |
| Sterculia urens | Bark | -- | -- | * | |
| Foeniculum vulgare | Fruit | -- | -- | * | |
| Althaea officinalis | Flower | -- | -- | * |