| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Cnicus benedictus | Plant | 0.5 | 3.4 | -0.3 | * |
| Cocos nucifera | Seed | -- | 0.02 | -0.3 | Furr, A.K., et al. 1979 |
| Corylus avellana | Seed | 0.01 | 0.08 | -0.3 | * |
| Crataegus rhipidophylla | Fruit | -- | 20.0 | 4.6 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Crataegus laevigata | Fruit | 0.6 | 2.0 | 0.1 | * |
| Cucumis sativus | Fruit | 0.001 | 2.8 | 0.3 | * |
| Cucumis melo | Fruit | 0.003 | 0.004 | -0.4 | * |
| Cucurbita pepo | Seed | 0.08 | 0.4 | -0.3 | * |
| Curcuma longa | Plant | 0.5 | 1.6 | -0.4 | * |
| Cymbopogon citratus | Plant | -- | 62.0 | 2.3 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Cypripedium pubescens | Root | -- | 49.0 | 3.1 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Daucus carota | Root | 0.001 | 0.02 | -0.4 | * |
| Dioscorea villosa | Root | 0.2 | 0.8 | -0.3 | * |
| Dioscorea sp. | Root | -- | -- | * | |
| Echinacea spp | Root | -- | 0.5 | -0.3 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Echinacea purpurea | Root | 0.5 | 2.1 | -0.2 | * |
| Eleutherococcus senticosus | Root | 0.2 | 1.0 | -0.3 | * |
| Elytrigia repens | Plant | -- | 102.0 | 4.1 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Ephedra sinica | Plant | 0.3 | 1.2 | -0.4 | * |
| Equisetum arvense | Plant | 0.3 | 1.3 | -0.4 | * |