Data Views Total Plants: 2 CSV Excel PDF Total Activities: 1 Click on column headings to sort table by that column Plant Part Low PPM High PPM StdDev *Reference Rhododendron ferrugineum Leaf -- -- * Rhododendron ponticum Leaf -- -- * *Unless otherwise noted all references are to Duke, James A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press.