| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Mentha longifolia | Shoot | -- | -- | * | |
| Mentha x rotundifolia | Leaf | -- | -- | Jim Duke's personal files. | |
| Ribes nigrum | Bud | -- | -- | * | |
| Agathosma betulina | Leaf Essent. Oil | -- | -- | * | |
| Mentha x piperita | Leaf | 0.01 | 0.1 | -1.4 | Duke, J. A. Writeups or information summaries on approximately 2,000 economic plants, USDA, ARS, Beltsville, MD 20705. |
| Agathosma betulina | Leaf | 1800.0 | 3600.0 | 0.7 | * |
| Barosma betulina | Leaf | 1800.0 | 3600.0 | 0.7 | * |