Mountainous regions are unique for investigating morphological and biochemical adaptations of plants on the environment. The reason for that are with altitude quickly changing environmental conditions. In this study we investigated morphological and biochemical traits of Helianthemum grandiflorum in heterogeneous radiation conditions in central Julian Alps. To get heterogeneous radiation conditions we sampled plants from two different altitudes and placed filters with different ultraviolet (UV) transmission grades above the plants. Analyses of morphological traits showed mainly differences between the first and second sampling period. This was due to the time of first sampling period, which was at the start of the growing season, where plants from both sampling locations were not yet fully developed. We observed a thicker upper cuticle under the UV absorbing filter (UV-) in comparison to the filter that transmits UV. The reason for this is a mutual effect of epicuticular waxes and UV-absorbing compounds as protective mechanisms against UV and in some cases the precedence of one before another. We observed higher concentrations of UV-B absorbing compounds on the higher altitude site in natural radiance conditions compared to plants under UV- filter, where concentrations were the same on both sites. Optical properties of leaves were very similar under different UV regimes. The results of this study show a good adaptation of the species to the current environment.