Data Views Total Plants: 21 CSV Excel PDF Total Activities: 5 , Previous12 Show all rows. Paginate rows. Click on column headings to sort table by that column Plant Part All Fruit Leaf Plant Root Seed Seed Essent. Oil Silk Stigma Style Sprout Seedling Low PPM High PPM StdDev *Reference Zea mays Root -- -- * *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.