Data Views Total Plants: 21 CSV Excel PDF , Previous12 Show all rows. Paginate rows. Click on column headings to sort table by that column Plant Part All Flower Fruit Herb Leaf Plant Seed Silk Stigma Style Tuber Low PPM High PPM StdDev *Reference Zea mays Seed 190209.0 838000.0 1.2 * *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.