Plants need light to grow. They use energy from sunlight to produce organic carbon. However, new findings – including my own work – now hint that up to 35% of all plant species can also obtain carbon from root-associated fungi when light availability is insufficient for growth. This calls into question much of what we thought we knew about how plants survive in the understory. The goal of MIXOTROPH project is to determine the frequency and magnitude of this newly discovered form of ‘mixotrophy’ in our terrestrial ecosystems. I will achieve this exciting goal by working at the intersection of physiology, ecology, evolutionary and molecular biology.