The pomological characteristics of leaves, fruits and size were studied of trees of offspring of crossings of Blackthorn with: /1/ Green Renclod, /2/ Yellow Ablanshka plum and /3/ Topalka. Hybridization was conducted by Prof. Micho Balev. The power of influence of parental forms was studied over the inheritance of examined indicators for the offspring. Studies were conducted in the period of finished growth of trees. Maternal form had a height of 1.9m. Paternal forms - Green Renclod, Yellow Ablashka and Topalka had the following heights: 7.4, 5.5, 5.9m and trunk circumference: 108, 47, 48cm. In the first combination, the height of trees from the offspring in most cases was 6-7m, and the trunk circumference was 60-80cm. In the second and third crossings, the following plant height was predominant, respectively: 4.5-5.5m and 4,3-6,3m, and trunk circumference was: 50-70cm and 60-86cm. All plants from the offspring for all three combinations had great growth vigour, as in relation to the values of the main parameters of that indicator they got closer to the paternal forms. The same tendency was also found in the inheritance of leave sizes - i.e. a stronger influence of the paternal parent. For all offspring of the plants, fruits had blue colouring. In relation to weight of fruits, they took an intermediate position of the parents with a slight approaching to the parental forms. In the first combination, a greater share of the studied plants had a fruit weight 10-14g, and in the second one - 9-11g. A smaller weight had fruits of plants from the combination Blackthorn X Topalka, as almost half of them had a weight from 5 to 9g