Diversity of Phyllomorphic Branches in Conifers

Abstract

The structure of specialized vegetative shoots of conifers performing a trophic function has not been suffi ciently studied. The purpose of the work was to describe and classify phyllomorphic branches, as well as to identify the adaptations of conifers to the formation of such specialized trophic shoots. Phyllomorphic branches are fl attened dorsoventral shoots or systems of shoots with a non–thickened axis and opposite or regular double-row leaves. About 250 species of 42 genera of modern conifers cultivated in botanical gardens of Russia were studied. The main research method was a comparative morphological analysis of shoot systems, individual shoots and leaves. Several structural types of phyllomorphic branches have been identifi ed, each of which has its own variants: 1. Classical double-row fl at needle-shaped leaves with a thin axis (Abies, Amentotaxus, Cephalotaxus, Keteleeria, Picea, Podocarpus, Prumnopitys, Pseudotaxus, Pseudotsuga, Sequoia, Taxus, Torreya, Tsuga); 2. Phyllomorphic branches in the form of dorsiventral, branched in one plane systems of shoots (Chamaecyparis, Thuja, Glyptostrobus, Metasequoia, Taxodium); 3. Phyllomorphic branches that have phyllocladia instead of leaves (species of the genus Phyllocladus).