ИСТИНА

The conservation of plant species' diversity should also include that of cultivated varieties; the latter derive from artificial selection and hybridization of species which is used to develop economically valuable, altered or amplified qualities of plants. Ornamental plants are usually subjected to big changes aiming at decorative attributes and the produced varieties are treated as atypical structures or deviations from normal habit. During past centuries the richest gene pool of cultivated plants was collected in the botanical gardens. They demonstrate not only variety and stages of selection work, but also can be treated as a gene pool of atypical structures. An attempt is undertaken to describe observed atypical structures for forms and varieties of different species of Paeonia L., to trace the hereditary basis of different varieties, and the regularity of transfer of selected features from parental species to cultivars. Our researches have revealed significant polymorphism in alternation of flower parts, and also the modifications concerning reproductive organs. The type of alternation of flower parts does not depend on the cultivar origin. Besides flower structure, many conservative features of peonies, such as ploidy, ultrasculpture of pollen grains and surface of seeds are subjected to variability. As a result of the work we recorded direct dependence between loss of reproductive function and occurrence of atypical structures (doubleness, fragrance) which occurs because of the increase of flower apical meristem sizes during the formation of plant organs. Thus it is important to keep and study collections of forms and varieties of plants with atypical structures in botanical gardens since in the wild they are sporadic and solitary. Representing a unique combination of genes, any loss of a variety is irreplaceable. Therefore conservation of cultivated plants is one of the aims of botanical gardens along with conservation of wild species.