| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Ocimum basilicum | Leaf | 4100.0 | 4340.0 | 0.1 | USDA's Ag Handbook 8 and sequelae) |
| Oenothera biennis | Seed | 4300.0 | 5300.0 | 0.9 | * |
| Oenothera biennis | Herb | 2700.0 | 3900.0 | -0.7 | * |
| Ophiopogon japonicus | Tuber | 390.0 | 410.0 | -0.9 | * |
| Opuntia ficus-indica | Seed | -- | 790.0 | -0.9 | Laferriere, J.E., 1988, Nutricomp Program, Nutricomp Database; reviewed in J. Ethnobiology 9(1):27-29. |
| Opuntia ficus-indica | Bud | -- | 1420.0 | -1.0 | Laferriere, J.E., 1988, Nutricomp Program, Nutricomp Database; reviewed in J. Ethnobiology 9(1):27-29. |
| Origanum vulgare | Plant | 2600.0 | 3016.0 | -0.3 | USDA's Ag Handbook 8 and sequelae) |
| Origanum majorana | Plant | 3300.0 | 3900.0 | -0.1 | USDA's Ag Handbook 8 and sequelae) |
| Oryza sativa | Plant | 1100.0 | 2200.0 | -0.6 | * |
| Pachyrhizus erosus | Tuber | 160.0 | 1475.0 | -0.1 | * |
| Paeonia suffruticosa | Root Bark | 930.0 | 1180.0 | -1.2 | * |
| Paeonia moutan | Root Bark | 930.0 | 1180.0 | -1.2 | * |
| Paeonia lactiflora | Root | 580.0 | 990.0 | -0.8 | * |
| Panax quinquefolius | Plant | 980.0 | 2200.0 | -0.6 | * |
| Panax japonicus | Rhizome | -- | 2400.0 | 0.8 | * |
| Panax ginseng | Root | 102.0 | 481.0 | -1.1 | * |
| Panicum maximum | Leaf | -- | 4500.0 | 0.1 | ANON. 1948-1976. The Wealth of India raw materials. Publications and Information Directorate, CSIR, New Delhi. 11 volumes. |
| Papaver somniferum | Seed | 3148.0 | 15600.0 | 5.0 | * |
| Parthenium integrifolium | Root | 320.0 | 2000.0 | -0.3 | * |
| Passiflora incarnata | Flower | 275.0 | 2500.0 | -0.2 | * |