Abstract
In the past function of mycorrhizas has been examined at the level either of the isolated individual root or of the individual entire plant. It is shown here that ectomycorrhizal mycelial strands can extend from plant to plant, thus initiating infection in seedlings, and that the resulting fungal interconnections provide functional pathways for the transfer of labelled assimilate between individuals. Mycelial strands also provide a pathway for the transport of physiologically significant quantities of water. Strand functions are examined in relation to structure, and their role as morphological and physiological extensions of the root system is emphasized. Pinus sylvestris and Suillus bovinus were the text organisms.