| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Calendula officinalis | Plant | 10000.0 | 17500.0 | 1.7 | * |
| Camellia sinensis | Seed Oil | -- | -- | * | |
| Camellia sinensis | Seed | -- | -- | * | |
| Capparis spinosa | Plant | -- | -- | * | |
| Capsicum frutescens | Resin, Exudate, Sap | -- | -- | * | |
| Carica papaya | Seed Oil | -- | 4000.0 | -0.7 | Jim Duke's personal files. |
| Carica papaya | Flower | -- | -- | Jim Duke's personal files. | |
| Carica papaya | Seed | -- | -- | List, P.H. and Horhammer, L., Hager's Handbuch der Pharmazeutischen Praxis, Vols. 2-6, Springer-Verlag, Berlin, 1969-1979. | |
| Carica papaya | Leaf | -- | -- | Jim Duke's personal files. | |
| Carica papaya | Fruit | 10.0 | 90.0 | -0.4 | * |
| Carthamus tinctorius | Seed | -- | -- | * | |
| Carum carvi | Seed | 100.0 | 110.0 | -0.5 | USDA's Ag Handbook 8 and sequelae) |
| Carum carvi | Fruit | 100.0 | 110.0 | -0.4 | * |
| Carya illinoensis | Leaf | -- | -- | * | |
| Cinnamomum camphora | Plant | -- | -- | * | |
| Cinnamomum verum | Seed | 260000.0 | 304000.0 | 2.2 | Wealth of India. |
| Citrullus colocynthis | Petiole | -- | -- | * | |
| Citrullus lanatus | Seed | 1600.0 | 3250.0 | -0.5 | ANON. 1948-1976. The Wealth of India raw materials. Publications and Information Directorate, CSIR, New Delhi. 11 volumes. |
| Citrus reticulata | Seed Oil | -- | -- | * | |
| Cocos nucifera | Seed | 25754.0 | 431400.0 | 3.4 | * |