The fungus brings sugar to the trees' roots

That means that the sugars flow from the tree roots into the fungal hyphae.Once the sugars enter the fungus,they travel along the hyphae through pores between cells or through special hollow transporter hyphae.The fungus absorbs some of the sugars,but some travels on and enters the roots of a neighboring tree,a seedling that grows in the shade and has less opportunity to photosynthesize sugars.