Materials storage retaining walls

Most of the cells of wood are long, narrow hollow fibers and tubular-shaped cells arranged with their long axes parallel to the axis of the tree trunk. Certain food storage cells lie in radial bands, termed wood rays, which are perpendicular to the tree axis. The walls of this complex system of plant cells form the basic framework and material of all wood substance, All wood substance is composed of two basic chemical materials, lignin, and a polysaccharidic system, which is termed holoceliulose. The latter embraces cellulose and the hemicelluloses, a mixture of pentosans, hexosans and polyuronides, and in some instances small amounts of pectic materials. Wood cell wall tissue also always retains small amounts of mineral matter (ash). 

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