Seed of Acer pseudoplatanus was obtained from six widely scattered locations in Europe, and seedlings from these seed-sources were grown on 25 different soils, covering a wide range of soil properties. Seedlings from four seed-sources of Betula verrucosa were also grown. There was a very wide variation in growth on the different soils, and between the two species; but relatively little variation between seed-lots within a species, and no significant interaction between seed-lot and soil, over the 2-year period of the experiment. It is concluded, therefore, that any one of the seed-lots used in this experiment could have been used to assess the response of seedlings of that species to changes in soil type, and that variation in growth due to genetic differences within these species is likely to be small in comparison to the variation due to soil conditions.