| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Canarium indicum | Seed | -- | 136210.0 | 0.2 | * |
| Cannabis sativa | Seed | 207000.0 | 250600.0 | 1.2 | * |
| Capparis spinosa | Seed | 142200.0 | 183600.0 | 0.7 | Wealth of India. |
| Capparis spinosa | Plant | -- | -- | * | |
| Capparis spinosa | Flower | 700.0 | 2115.0 | 0.1 | * |
| Capsicum annuum | Fruit | 2190.0 | 29871.0 | 0.1 | * |
| Capsicum frutescens | Fruit | 1040.0 | 8486.0 | -0.2 | USDA's Ag Handbook 8 and sequelae) |
| Carica papaya | Seed | -- | 5389.0 | -0.9 | * |
| Carica papaya | Flower | -- | -- | Jim Duke's personal files. | |
| Carica papaya | Fruit | 60.0 | 537.0 | -0.3 | * |
| Carica papaya | Leaf | -- | -- | Jim Duke's personal files. | |
| Carica papaya | Seed Oil | -- | 4000.0 | -1.5 | Jim Duke's personal files. |
| Carthamus tinctorius | Seed | 122000.0 | 481394.0 | 3.2 | * |
| Carum carvi | Fruit | 20300.0 | 46714.0 | 0.3 | * |
| Carum carvi | Seed | 19600.0 | 46714.0 | -0.5 | * |
| Carya illinoensis | Leaf | -- | -- | * | |
| Catalpa bignonioides | Seed | 17075.0 | 129200.0 | 0.2 | * |
| Caulophyllum thalictroides | Root | -- | -- | Jim Duke's personal files. | |
| Cedrus deodora | Seed | -- | 42465.0 | -0.6 | * |
| Ceiba pentandra | Seed | 52000.0 | 145200.0 | 0.3 | * |