| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Quisqualis indica | Fruit | -- | 0.01 | -0.5 | * |
| Raphanus sativus | Root | -- | -- | * | |
| Rheum rhabarbarum | Pt | -- | 0.01 | * | |
| Rhodymenia palmata | Plant | -- | 33.0 | 1.3 | * |
| Ribes uva-crispa | Fruit | -- | -- | * | |
| Ribes rubrum | Fruit | 0.01 | 0.18 | -0.3 | * |
| Ribes nigrum | Fruit | 0.01 | 0.06 | -0.5 | ACTA AGRIC SCAND SUPPL 22: 1980 |
| Rosa laevigata | Fruit | -- | 0.17 | -0.3 | * |
| Rubia cordifolia | Root | -- | 1.1 | -0.2 | * |
| Rubus chamaemorus | Fruit | -- | -- | * | |
| Rubus chingii | Fruit | -- | 0.14 | -0.4 | * |
| Salvia miltiorrhiza | Root | -- | 0.34 | -0.2 | Chen, H.C. and Lin, S.M. 1988. Determination of Mineral Elements in Certain Crude Drugs (Part 1), Kaohsiung J. Med. Sci., 4: 259-272. |
| Schisandra chinensis | Fruit | -- | 0.18 | -0.3 | Chen, H.C. and Lin, S.M. 1988. Determination of Mineral Elements in Certain Crude Drugs (Part 1), Kaohsiung J. Med. Sci., 4: 259-272. |
| Scrophularia buergeriana | Root | -- | 0.13 | -0.2 | * |
| Scutellaria baicalensis | Root | -- | 0.18 | -0.2 | Chen, H.C. and Lin, S.M. 1988. Determination of Mineral Elements in Certain Crude Drugs (Part 1), Kaohsiung J. Med. Sci., 4: 259-272. |
| Siegesbeckia orientalis | Plant | -- | 0.25 | -0.4 | * |
| Sinapis alba | Seed | -- | 0.05 | -0.3 | * |
| Solanum tuberosum | Tuber | 0.001 | 0.6 | -0.2 | * |
| Solanum melongena | Fruit | 0.004 | 0.004 | -0.5 | * |
| Sophora subprostrata | Root | -- | 0.23 | -0.2 | * |