| Abbreviation | Definition |
|---|---|
| OC | Organic Content |
| OCBG | Oklahoma Centennial Botanical Garden |
| OEC | Oxygen-Evolving System |
| OG | Organic Gardening |
| OIPC | Ontario Invasive Plant Council |
| OP | Open Pollinated |
| OPBG | Olive Pink Botanic Garden |
| OPC | Oligomeric ProanthoCyanidin |
| OPC | Oligomeric Proanthocyanidins |
| OPV | Open Pollinated Varieties |
| ORIG | Origination |
| OS | Orzya Sativa |
| OSL | Optical Stimulated Luminescence |
| OTU | Operational Taxanomic Unit |
| OVG | Organic Vegetable Garden |
| OVN | Orchard, Vineyard, and Nursery |
| OWB | Old World Bluestem |
| OXL | Oxalis |
| OXS | OrganicXseeds database |
| P | Plant |