SUMMARY
The aim of the work is to analyze several morphological signs of Arctium plants of Ukrainian flora and to carry out their comparative analysis using the method of determination of the measure of discrepancy by the separate parameters and similarity measure, offered by Shmidt. For comparison there was used the normalize deviation and coefficient of signs divergence. The putting of normalize deviation on the graph gives the visible presentation about the divergence measure of signs of studied objects. The graphs of normalize deviations of morphometric signs of Arctium species relative to A. Lappa standard were constructed on the base of received results. Among the sings of Arctium plants were used the ones that had reliable deviations relative to the standard. The analysis of values of divergence coefficient showed the measure of general similarity of the whole complex of studied signs relative to the standard values. As a result of research it was revealed, that the species A. nemorosum and A. Lappa are most similar by morphological parameters; in A.minus and A. tomentosum were revealed the maximal deviations of the signs. It allowed use these signs at diagnosis of interspecific differences and for the supplement of existing keys