The United States Department of Agriculture (USDA) regulates the importation of plants, including Plumeria, to prevent the introduction of harmful pests and diseases. The USDA requires that imported plants meet specific phytosanitary standards, and they may need to be accompanied by a phytosanitary certificate issued by the exporting country’s plant protection agency. Additionally, certain states within the US may have additional regulations regarding the importation of plants, so it’s essential to check both federal and state requirements before importing Plumeria.