| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Selenicereus grandiflorus | Plant | -- | -- | CRC Handbook of Medicinal Herbs and/or CRC Handbook of Proximate Analyses | |
| Portulaca oleracea | Herb | -- | -- | List, P.H. and Horhammer, L., Hager's Handbuch der Pharmazeutischen Praxis, Vols. 2-6, Springer-Verlag, Berlin, 1969-1979. |