| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Rheum palmatum | Rhizome | -- | 0.5 | * | |
| Coriandrum sativum | Fruit | -- | -- | Lawrence, B.M., Essential Oils 1976-1977, Essential Oils 1978, Essential Oils 1979-1980. | |
| Hypericum perforatum | Plant | -- | -- | Gruenwald, J. et al. 1998. PDR for Herbal Medicine. 1st ed. Medical Economics Co., Montvale, NJ. 1244 pp. (abbreviated as PHR or Physicians Herbal Reference in my mind) | |
| Citrus reticulata | Fruit | -- | 1.0 | Lawrence, B.M., Essential Oils 1976-1977, Essential Oils 1978, Essential Oils 1979-1980. | |
| Petasites hybridus | Leaf | -- | -- | Wichtl, M. 1984. Teedrogen. Ein Handbuch fur Apotheker und Arzte. Wissenschaftliche Verlagsgesellscharft. mbH Stuttgart. 393 pp. | |
| Eruca sativa | Hs | -- | -- | * |