In the study a new method has been applied, which allows us to identify the absorption, movement and localization of nanoparticles in plants. To do this, absorption of nanoparticles into root cells and their spread in the leaves have been investigated by EPR using iron oxide nanoparticles. The analysis of the EPR signals of elodea leaves, soaked in solutions of iron nanoparticles is confirms that nanoparticles can be absorbed by the plant cells and spread to organs. Iron nanoparticles have been also shown to penetrate the plant seeds.