Data Views Total Plants: 2 CSV Excel PDF Click on column headings to sort table by that column Plant Part All Essential Oil Leaf Essent. Oil Low PPM High PPM StdDev *Reference Juglans nigra Essential Oil -- 12000.0 * Aspalathus linearis Leaf Essent. Oil -- 4000.0 * *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.