The purpose of this work is to identify the level of phenotypic diversity of the morphological features of Populus × sibirica leaves, including qualitative signs-phenes. To reveal the variability, the authors examined 90 trees, on which 1,350 leaves were measured in the green areas of the cities of Novosibirsk, Novokuznetsk and Berdsk. When analyzing the qualitative features, there were selected the following morphological markers: leaf pubescence, development of basal glands, leaf form, its base and apex. The conducted studies of Populus × sibirica samples showed that it is characterized by very low and low variability of the quantitative traits of a leaf. Leaf-shaped ovoid plates and leaves with developed basal glands (78–89 %) are predominant. Close indicators of averaged endogenous and individual variability reflect its cultural origin. Probably, Populus × sibirica in the Siberian region consists of several clones selected from the same hybrid family. A number of studied morphological qualitative features of a leaf, which are distinguished by the absence of endogenous variability, can be attributed to phenes: the shape of the apex and the shape of the base of the lamina, as well as the nature of the development of pubescence. The most controversial issue in the origin of Populus × sibirica remains the presence of basal glands at the base of the leaf blade.