Fungal symbiosis with early land plants Hundreds of millions of years ago, evolved descendants of aquatic plants began showing up on dry land. These newly terrestrialized species had to deal with increased ultraviolet light exposure, desiccation, and less accessible nutrients. Rich et al. show how mutualist fungi may have helped these nascent plant lineages with adaptation to their newly challenging environment (see the Perspective by Bouwmeester). Genetic and metabolic analysis of a liverwort as a representative of such plants suggests that the mutually beneficial exchange of nutrients with arbuscular mycorrhizal fungi may have been a feature of these most early land plants. Science , abg0929, this issue p. 864 ; see also abi8016, p. 789