| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Hedeoma pulegioides | Plant | -- | -- | * | |
| Mentha pulegium | Essential Oil | -- | -- | * | |
| Viola odorata | Leaf | -- | -- | * | |
| Citrus paradisi | Fruit | -- | -- | Guenther, E., The Essential Oils, 6 volumes, D. van Nostrand, New York, 1948-1952. |