Research of the flora of some areas of the Central Russian forest-steppe shows that a number of plants has deviations from the main species characteristics. The fact that there is a continuous series of variations from individual to species level in nature has long been known for a long time (Darwin, 1991). The reasons and results of this are very different and unpredictable. The ability of plants to change their phenotype is genetically determined. The scope of intraspecific differentiation depends on many external causes. The intraspecific potential of plants reveals itself when ecological situation and geographical fragmentation modify. In result, populations which significantly differ from the main genotype are formed. The impact of new environmental conditions is shown in the examples of Genista tinctoria L., Achillea millefolium L., Salvia pratensis L. The Trifolium lupinaster or Lupinaster pentaphyllus is an example of the introduction of geographically distant genetically stable races. Some species can be represented by different morphobiotypes. For example, erect (haying) and lying (pasture) forms of Lotus corniculatus, Medicago falcata, Astragalus onobrychis. There are some transitional forms. Populations of tall and low growing Anemone sylvestris were observed. A pronounced manifestation of intraspecific diversity is the polychrome of flowers. It was found in рlants from different families: species of iris, Schrenka tulip (Tulipa suaveolens), lily of the Saranka (Lilium pilosiusculum) and others. The collection of the botanical garden for over 20 years contains garden forms of plants of natural flora, which appeared due to spontaneous new formations. These are variegated forms of Aegopodium podagraria and Galeobdolon luteum. The results of the introduction of species and intraspecific diversity of rare and economically valuable plants in the Botanical garden of the Voronezh state University are presented.