Lotus corniculatus is a highly diverse legume with good adaptability to different soil and climatic conditions. The objective of this research was to estimate the phenotypic diversity of individual L. corniculatus plants growing under two different habitat types with different grazing management. The collection of plant material was conducted in four forested and four open grassland sites in northern Greece. Plants from open grassland had significantly lower leaf area, leaf perimeter, leaf length, leaf width and internode length compared to those from the forest. This morphological differentiation could be contributed to by differences in grazing intensity. Plants from open grasslands had significantly higher total phenols and condensed tannins, but lower crude protein content compared to those from the forest. Environmental factors in association with grazing management are the main contributors to the highly divergent concentrations of phenols, tannins and condensed tannins.