Attempts to reduce consumption of fossil fuels have led to increased use of biofuels. Although willow generates a high energy exchange and is profitable in relation to many other dedicated energy crops, there has been relatively low interest among farmers in growing willow. This low interest is expected to continue unless the profitability of willow growing is considerably increased, either by significantly reducing production costs or by increasing product price. This could be achieved if growers could guarantee production of a certain quantity and quality at a certain time, which would require e.g. a method to estimate standing biomass in willow plantations. This study evaluated if visual interpretation of low altitude aerial photography from a small unmanned aircraft can be used to detect and map differences in variety, homogeneity, and biomass density in growing willow. It is the initial part of a larger project to evaluate different remote sensing based methods for estimation of biomass in growing willow. The ability to accurately map within-field variability would be very useful since it enables more efficient stratified field sampling techniques to be used. If differences can be detected by means of visual interpretation it could mandate the development of more advanced automated image-analysis based tools for quantitative measurements. The results show that it was possible to map areas with different homogeneity with high spatial precision using the orthophoto mosaic images generated with the UAS, when considering both spectral and textural information. It was also possible to differentiate between different varieties of willow using the UAS, provided that single images were used for spectral differentiation and that the stands were sufficiently large.