Experiments in intraspecific hybridization of Siberian stone pine, not just of this species but of different regional origins as well, have been carried out at a clone plantation in Middle Siberia (Krasnoyarsk forest- steppe). Crossings were realized using the principle of ecologo-geographical remoteness of populations. Siberian stone pine clones chosen for crossing had good growth and constant reproductive ability over many years. An analysis of the characteristics of hybrid female cones (weight, linear size, number of developed scales) and seeds (number, weight, seed fullness, viability) showed the positive influence of controlled pollination with combinations of different climatypes. The study of hybrid growing climatypes, resulting from crossing of the plain and mountain populations, also revealed signs of heterosis. Research Material