Аннотация: The results of developmental and structural studies on three leaf formations of generative
shoots of Nandina, Mahonia and Helleborus species of different eco-geographical origin from native
area and introduced ones are outlined here. The development of three leaf formations (cataphylls,
assimilative leaves, bracts) from different parts of leaf primordia, in our view, is the base of leaf
heterogeneity. The results of comparative studies of developmental and anatomical structures show
that homological formations (cataphylls and assimilative leaf bases) of shrubs and herbaceous forms
are characterized by their considerable similarity. More vigorous development of leaf bases are due to
their multifunctionality. Amphistomacy and the presence of homogenous mesophyll are distinctive
features of cataphylls and bracts, unlike assimilative leaf laminas. Cataphylls of herbaceous forms lack
many special defensive features which are characteristic of many woody ones. The defensive function
of cataphylls is supplied by anatomical features of the epidermal complex and by the presence of
anthocyans and tannin substances as well. Great anatomical similarity of bracts and sepals are revealed.
It confirms the possibility of bracteous origin of the calyx in Berberidaceae and Ranunculaceae.