The Structure of hardwoods

Abstract

The secondary xylem of dictotyledons is commonly called hardwood largely for historical reasons. It is considerably more complex than the wood of conifers because it contains a greater variety of cell types (Fig. 130). Whereas in softwoods the functions of conduction and support are performed by the one axial cell type — the tracheid — in most hardwoods these functions are carried out by different cell types. Vessels, built up of individual vessel elements joined end to end provide a pathway for the conduction of water and solutes up the trunk of the living tree, while long thick-walled fibres, variously grouped, function in support. Axial parenchyma cells are usually more abundant in hardwoods than in softwoods and the rays occupy a higher proportion of the wood volume with large multiseriate rays common in many species.