| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Punica granatum | Fruit | -- | -- | * | |
| Pyrus communis | Pericarp | -- | 28.0 | -1.0 | * |
| Quercus infectoria | Leaf | -- | -- | * | |
| Quercus alba | Bark | -- | -- | List, P.H. and Horhammer, L., Hager's Handbuch der Pharmazeutischen Praxis, Vols. 2-6, Springer-Verlag, Berlin, 1969-1979. | |
| Quercus velutina | Plant | -- | -- | * | |
| Quercus robur | Bark | -- | -- | * | |
| Rhododendron dauricum | Plant | -- | -- | * | |
| Rhus coriaria | Leaf | -- | -- | Hansel, R., Keller, K., Rimpler, H., and Schneider, G. eds. 1992. Hager's Handbuch der Pharmazeutischen Praxis, Drogen (A-D), 1209 pp., 1993 (E-O), 970 pp., 1994 (P-Z), 1196 pp. Springer-Verlag, Berlin. | |
| Rhus toxicodendron | Plant | -- | -- | * | |
| Ribes nigrum | Fruit | -- | -- | List, P.H. and Horhammer, L., Hager's Handbuch der Pharmazeutischen Praxis, Vols. 2-6, Springer-Verlag, Berlin, 1969-1979. | |
| Ribes nigrum | Fruit Juice | -- | -- | * | |
| Ricinus communis | Plant | -- | -- | * | |
| Rosa spp | Fruit | -- | -- | * | |
| Rosa damascena | Flower | -- | -- | * | |
| Rubus idaeus | Juice | -- | -- | * | |
| Rumex acetosa | Fruit | -- | -- | * | |
| Rumex crispus | Leaf | -- | -- | * | |
| Ruta graveolens | Plant | -- | -- | * | |
| Salix alba | Bark | -- | -- | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. | |
| Sambucus nigra | Leaf | -- | -- | * |