| Abbreviation | Definition |
|---|---|
| APHA | Animal and Plant Health Association |
| APHD | Andhra Pradesh Horticulture Department |
| APHF | Associacaeo Portuguesa de Horticultura e Fruticultura |
| APHIS | Animal and Plant Health Inspection Service |
| APIRS | Aquatic Plant Information Retrieval System |
| APIS | Aquatic Plant Information System |
| APMS | Aquatic Plant Management Society |
| APRS | Alien Plants Ranking System |
| APTY | American Purple Top Yellow Rutabaga seed |
| AQIS | Australian Quarantine and Inspection Service |
| AQIS | Australian Quarantine Inspection Service |
| AQSIQ | Administration of Quality Supervision Inspection and Quarantine |
| ARPV | Apricot Ring Pox Virus |
| ASBS | Australasian Systematic Botany Society |
| ASG | Arboriculture Specialist Group |
| ASMD | Available Soil Moisture Depletion |
| ASW | Available Soil Water |
| AT | Arabidopsis Thaliana |
| ATDN | Amazon Tree Diversity Network |
| ATV | A Tree Viewer |