Data Views Total Plants: 81 CSV Excel PDF Show All Paginate , Previous12345 Click on column headings to sort the list on the column Plant Part All parts ... Bark Bulb Fruit Leaf Plant Root Root Bark Seed Shoot Stem Tuber Low PPM High PPM StdDev *Reference Zea mays Seed 0.06 63.0 1.6 * *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.