Tree vegetation elements directly influence the stability of composition of many historical gardens and parks. On the basis of a correct dendrological investigation it is possible to get information usable for the assessment of dendrological potential. On the example of ten historical parks in the Czech Republic the possibility of interpretation of dendrological potential is demonstrated. It is interpreted as an ability of the existing tree vegetation elements of the given subject to ensure the stability of its composition. It is suggested to use the standard attributes of vegetation elements – gardening value and age. It was demonstrated on the assessment example of these selected subjects that the definitive values of dendrological potential are significantly different and well describe the differences among subjects. In search for a more detailed answer to the causes of stability or instability of compositions it is possible to use the same data, e.g. for evaluation of the dominant taxons.