Carbon can be bi-directionally transferred between plants via common mycorrhiza network (CMN) in the soil. However, the chemical forms of this carbon are still unknown. In my MSc project, I investigated and attempted to identify the carbon metabolites transferred via direct hyphal connections between roots of different tree species. For this purpose, I used two experimental platforms. The first is a 13C pulse labeling experiment performed on oak and pine saplings in a controlled environment that allows only mycorrhiza to connect neighboring trees. Furthermore, we shaded some of the saplings to examine the effect of increased carbon demand on the flux and composition of carbon metabolites. The second is a complementing 13CO2 tree labeling experiment in the forest where I collected the mycorrhiza fruiting bodies and identified the carbon metabolites transferred within the CMN. We showed that carbon was transferred to the tree roots exudates, and later from the labeled tree to its neighboring fungi fruiting bodies, within four days. Discovering what materials are transferred can shed light on the role of this phenomenon and its potential benefits for the participating trees and fungi.