The Republic of Azerbaijan with a rich biodiversity occupies a special place in the Caucasus region. There are about 5000 higher plant species in the country (belonging to 1142 genera), which makes up 66% of the total number of plant species growing in the Caucasus. Among the widespread plant species in this rich nature, the Hypericum genus which belongs to the Hypericaceae family takes special place. Although the vast majority of species belonging to the Hypericaceae family are perennial, annual grass, shrub (47%), among them are semi-shrubs and, in rare cases, low trees (H. bequaertii De Wild., H. revolutum Vahl, H. canariense L. (5%) and aquatic (H. elodes L.) plants. Hypericum genus, which has about 500 species, 70 subspecies, 3 varieties and 11 hybrids in the world are represented by 19 species, 1 subspecies and 1 variety in the flora of Azerbaijan. The present article is part of a complex experimental study which comprises bioecological research studies of Hypericum L. in flora of Azerbaijan.