Secondary Xylem

Secondary xylem, more commonly known simply as wood, is the tissue produced by the vascular cambium on its inner face, and its study by preparing microscope sections is called xylotomy. Like the cambium that produces it, secondary xylem has two structural components: an axial system of vertical files of tracheary elements, fibres and wood parenchyma, running along the organ's long axis, and a radial system of rows of parenchymatous ray cells oriented at right angles to that axis, connecting the axial files sideways. The exact composition of secondary xylem - the relative amounts of vessels, tracheids, fibres and parenchyma, their density, and other properties - varies considerably from species to species, but broadly falls into two types based simply on whether vessels are present. Porous wood or hard wood is dicotyledonous wood that contains vessels (e.g. Morus r …