The purpose of the study was carrying out com-parative analysis of variability of annual seedlings of Mongolian oak and Ussuriisk plums, the copies were grown up from the seeds, selected in the tree nursery of SIBSAU. The seeds from the selected individuals were seeded in a tree nursery in the fall of 2015. At the end of vegetative period of 2016 the examining of the plants was carried out: the height stalk and the diameter at the root collar were measured, the number of leaves was determined. As a result of conducted researches it was estab-lished that in the seedlings of Mongolian oak on the height A598-3 family seedlings had the best indica-tors. Stalk diameter did not show any reliable dis-tinctions between the families. By the quantity of leaves the posterity of A598-3 family appeared the best. In plum Ussuri the height advantage seed-lings had A612-3 family; the diameter of the stalk was the best in V82-5. From the information given above, it is possible to draw the conclusion that the seed posterity of Mongolian oak and plums Ussuriisk is characterized by considerable variabil-ity reflecting its hereditary heterogeneity and can serve for the solution of selection tasks for the as-sessment of natural selection orientation in certain ecological conditions. Allocated copies should be used for further reproduction. The calculated coeffi-cients of height heritability specify that in the seed-lings grown up in uniform ecological conditions, the variability is caused first of all by genotype.