| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Hordeum vulgare | Plant | -- | -- | List, P.H. and Horhammer, L., Hager's Handbuch der Pharmazeutischen Praxis, Vols. 2-6, Springer-Verlag, Berlin, 1969-1979. | |
| Anethum graveolens | Seed Essent. Oil | -- | -- | * | |
| Olea europaea | Stem | -- | -- | Chemical Constituents of Oriental Herbs (3 diff. books) | |
| Taraxacum officinale | Flower | -- | -- | * | |
| Aesculus hippocastanum | Bark | -- | -- | Bisset, N.G., ed. 1994. Herbal Drugs and Phytopharmaceuticals. CRC Press. Boca Raton, FL. 566 pp. | |
| Viburnum opulus | Bark | -- | -- | ANON. 1948-1976. The Wealth of India raw materials. Publications and Information Directorate, CSIR, New Delhi. 11 volumes. | |
| Viburnum prunifolium | Bark | -- | -- | * |