The fungal cells grew in a web around each plant cell, like a hair net covering a chef’s head. The plant passed photosynthetic sugars through its cell walls to the adjacent fungal cell. The fungus needed this sugary meal to grow its network of fungal threads through the soil to pick up water and nutrients. In return, the fungus delivered these soil resources back to the plant, through the layers of pressed-together fungal and plant cell walls, in a two-way market exchange for the photosynthetic sugars.
