| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Oenothera biennis | Seed | 63000.0 | 83000.0 | -0.6 | * |
| Olea europaea | Fruit | -- | 782000.0 | 0.0 | CRC Handbook of Medicinal Herbs and/or CRC Handbook of Proximate Analyses |
| Opuntia ficus-indica | Fruit | 814000.0 | 864000.0 | 0.4 | * |
| Opuntia ficus-indica | Bud | -- | 952600.0 | 1.0 | Laferriere, J.E., 1988, Nutricomp Program, Nutricomp Database; reviewed in J. Ethnobiology 9(1):27-29. |
| Opuntia ficus-indica | Seed | 53000.0 | 136000.0 | -0.4 | * |
| Origanum vulgare | Plant | 68380.0 | 74820.0 | -3.0 | USDA's Ag Handbook 8 and sequelae) |
| Origanum majorana | Plant | 74920.0 | 77880.0 | -3.0 | USDA's Ag Handbook 8 and sequelae) |
| Oryza sativa | Seed | -- | 103000.0 | -0.5 | * |
| Oxalis tuberosa | Root | 824000.0 | 838000.0 | 0.5 | * |
| Pachira macrocarpa | Seed | -- | 54000.0 | -0.7 | * |
| Pachyrhizus erosus | Tuber | -- | 891500.0 | 1.0 | * |
| Panax ginseng | Root | -- | 788000.0 | 0.1 | * |
| Papaver somniferum | Seed | 62250.0 | 73300.0 | -0.6 | * |
| Parthenium integrifolium | Root | -- | 840000.0 | 0.5 | * |
| Passiflora quadrangularis | Fruit | 800000.0 | 944000.0 | 0.8 | * |
| Passiflora mollissima | Fruit | 920000.0 | 926000.0 | 0.7 | * |
| Passiflora edulis | Seed | -- | 54000.0 | -0.7 | Morton, J.F., Major Medicinal Plants. 1977. Atlas of Medicinal Plants of Middle America. Bahamas to Yucatan. 1981. |
| Passiflora ligularis | Fruit | 699000.0 | 860000.0 | 0.4 | * |
| Passiflora edulis | Fruit | 751000.0 | 790000.0 | 0.1 | CRC Handbook of Medicinal Herbs and/or CRC Handbook of Proximate Analyses |
| Passiflora incarnata | Flower | -- | 890000.0 | 0.5 | * |