| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Dictamnus albus | Root | -- | 30.0 | List, P.H. and Horhammer, L., Hager's Handbuch der Pharmazeutischen Praxis, Vols. 2-6, Springer-Verlag, Berlin, 1969-1979. | |
| Zanthoxylum americanum | Plant | -- | -- | * | |
| Dictamnus angustifolius | Plant | -- | -- | Jeffery B. Harborne and H. Baxter, eds. 1983. Phytochemical Dictionary. A Handbook of Bioactive Compounds from Plants. Taylor & Frost, London. 791 pp. | |
| Zanthoxylum americanum | Leaf | -- | -- | * | |
| Zanthoxylum alatum | Root | -- | -- | ANON. 1948-1976. The Wealth of India raw materials. Publications and Information Directorate, CSIR, New Delhi. 11 volumes. | |
| Ruta graveolens | Plant | -- | -- | * |