| Abbreviation | Definition |
|---|---|
| ICTB | International Center for Tropical Botany |
| IDCG | Immature Dense Core Granule |
| IEB | Institute of Experimental Botany |
| IJMB | International Journal of Modern Botany |
| IL | Inoculated Leaf |
| ILTD | Indian Leaf Tobacco Development |
| IMBR | Indio Maiz Biological Reserve (Nicaragua) |
| IOCV | International Organization of Citrus Virologists |
| IOPI | International Organization for Plant Information |
| IPA | Indole-3-propionic acid |
| IPGRI | International Plant Genetic Resources Institute |
| IPM | Ideal Potting Media |
| IPN | International Plant Names index |
| IPNI | The International Plant Names Index |
| IPPC | International Plant Protection Convention |
| IRIS | Inland Region Iris Society |
| IRRI | International Rice Research Institute |
| ISC | Invasive Species Council of british columbia |
| ISDS | Invasive Species Data Service |
| ISEB | International Society of Environmental Botanists |