Data Views Total Plants: 1 CSV Excel PDF Click on column headings to sort table by that column Plant Part Low PPM High PPM StdDev *Reference Allium cepa Plant -- -- Hamilton, J. W. 1975. Chemical Examination of Seleniferous Onions, Allium cepa. Adv. Front Plant Sci., 30: 189-. *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.