How appropriate that at the turn of a century that has overseen a second industrial revolution in agriculture, there is an increasing appreciation of the central role played by the mycorrhizal symbiosis, first described in the latter part of the nineteenth century (Frank, 1885). Simply stated, nearly all families of plants form root symbiotic organs, termed mycorrhizas, with soil fungi belonging to all the main phyla, namely Zygomycotina, Ascomycotina, Basidiomycotina and the Fungi Imperfecti (Harley & Harley, 1987). The importance of this symbiosis in controlling plant nutrient status and growth is well established (Smith & Read, 1997), but a report in this issue now provides, long awaited, nitrogen and phosphorus budgets for mycorrhizal trees (Perez-Moreno & Read, pp. 301–309).