The carried out researches have revealed, that cool weather spring conditions resulted to the best preparation sapling a pedunculata oak (Q. robur L.) in to leas leaves. It has caused amicable to leas leaves. Otherwise there was an education of leaves in rather warm years. Oak have poorly been prepared for to leas leaves that resulted, wave education of leaves. Also specificity of to leas of leaves at posterity in polymorphic population and consanguine descendents of an oak is tracked. It is revealed, the beginning and the period of to leas of leaves at sapling cultivation from acorns margin of a large forest trees do not coincide. Specificity of to leas of leaves at consanguine sapling depends on genetic features of parent trees which possess the certain level of heterozygosis and specific combinative ability to be crossing to other trees. In a polymorphic population the percent sapling early and late to leas of leaves is approximately identical. Probably mechanisms of splitting of attributes in posterity and the balanced selection promote maintenance of genetic polymorphism in natural populations.