Data Views Total Plants: 64 CSV Excel PDF Total Activities: 28 , Previous1234 Show all rows. Paginate rows. Click on column headings to sort table by that column Plant Part All Bark Cob Cork Essential Oil Flower Fruit Fruit Juice Leaf Plant Resin, Exudate, Sap Rhizome Root Root Essent. Oil Seed Shoot Stem Stem Bark Wood Low PPM High PPM StdDev *Reference Zea mays Cob -- -- * Zea mays Shoot -- -- * Zea mays Seed 4.0 31.0 Jim Duke's personal files. Zingiber officinale Plant -- -- Stitt, Paul. Why George should eat broccoli. *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.