To clarify the morphological variations of Galium, its morphological characteristics were examined using maximum parsimony analysis. The key characteristics as well as the range of variation in each characteristic were investigated at the species level and were employed to elucidate the relationships between the taxa. This study confirmed that species belonging to genus Galium formed a monophyletic group and comprised two main clades. Sect. Cymogaliae and sect. Leptogalium are polyphyly groups, and other sections are monophyletic group. This study also suggests that the fruit hairs, the types of petal apexes, and the colors of the petals are the most valuable taxonomic characteristics for differentiating different sections. The numbers of the leaves and leaf shape provide useful taxonomic characteristics for the identification of different species.