| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Simmondsia chinensis | Seed | -- | 16.0 | -0.8 | * |
| Echinacea purpurea | Root | 1.3 | 5.1 | -0.8 | * |
| Echinacea spp | Root | -- | 5.1 | -0.8 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Astragalus membranaceus | Root | 0.8 | 5.0 | -0.8 | * |
| Spondias dulcis | Fruit | -- | 1.9 | -0.9 | * |
| Brassica rapa | Seed | -- | 15.0 | -0.9 | * |
| Opuntia ficus-indica | Seed | -- | 15.0 | -0.9 | Laferriere, J.E., 1988, Nutricomp Program, Nutricomp Database; reviewed in J. Ethnobiology 9(1):27-29. |
| Spondias tuberosa | Fruit | -- | 1.33 | -0.9 | * |
| Eleutherococcus senticosus | Root | 0.9 | 4.2 | -0.9 | * |
| Apium graveolens | Fruit | 0.3 | 1.2 | -0.9 | * |
| Inula helenium | Root | 1.0 | 3.9 | -0.9 | * |
| Parthenium integrifolium | Root | 0.6 | 3.7 | -0.9 | * |
| Centella asiatica | Bark | -- | 3.4 | -0.9 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Gentiana lutea | Root | 0.6 | 2.9 | -0.9 | * |
| Armoracia rusticana | Root | 0.5 | 2.9 | -0.9 | * |
| Symphytum officinale | Root | -- | 2.8 | -0.9 | Pedersen, M. 1987. Nutritional Herbology. Pederson Publishing. Bountiful, Utah. 377 pp. |
| Smilax officinalis | Root | 0.5 | 2.6 | -0.9 | * |
| Smilax spp | Root | 0.5 | 2.6 | -0.9 | * |
| Quercus stellata | Stem | 4.0 | 52.0 | -1.0 | * |
| Asparagus officinalis | Root | 0.2 | 2.3 | -1.0 | * |