| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Catharanthus roseus | Root | -- | -- | Rizk, A.F.M., The Phytochemistry of the Flora of Qatar, Scientific and Applied Research Centre, University of Qatar, Kingprint, Richmond, UK, 1986. | |
| Rauvolfia vomitoria | Root | -- | -- | * | |
| Rauvolfia tetraphylla | Plant | -- | -- | * |