Data Views Total Plants: 2 CSV Excel PDF Click on column headings to sort table by that column Plant Part All Fruit Essent. Oil Seed Low PPM High PPM StdDev *Reference Citrus limon Fruit Essent. Oil -- -- Jim Duke's personal files. Petroselinum crispum Seed -- 3.7 * *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.