Piloderma sp., a wood ash-colonizing ectomycorrhizal (EM) fungus, was grown symbiotically with Norway spruce in microcosms which contained granules of hardened wood ash. Mycelium close to the granules was sampled 3 times over a period of 11 weeks and the elemental content was investigated with particle induced X-ray emission. Mycelium from microcosms without wood ash was used as controls. The contents of P and K were similar in mycelium growing close to wood ash granules to those in control mycelium, while the Ca content increased from 23+/-21 mg g(-1) in controls to 63+/-8 mg g(-1) in mycelium growing close to wood ash granules. The Ca content was also increased in other parts of the mycelium more distant from the wood ash. Piloderma sp. may have a role in the short-term storage of Ca released from wood ash, rather than in releasing and storing P.