Hemicelluloses are short chains of branched hetero-polysaccharides composed of both hexoses and pentoses. D-xylose and L-arabinose are the main constituents of pentosans (xylans), while D-glucose, D-galactose and D-mannose are the main constituents of the hexosans (mannans). The major hemicelluloses component of softwood is mannan-based whilst the hemicelluloses in hardwoods are xylan-based. Hemicelluloses comprise 20-25 % of the material in hardwood and 7-12 % in softwoods. The close association of hemicelluloses with cellulose and lignin in the fibre cell walls contributes both rigidity and flexibility. The type and amount of hemicelluloses vary widely, depending on plant material, tissue type, growth rate, growth conditions, storage and method of extraction. A study of Pinus resinosa Ait has shown that the xylose content in earlywood was about 1-2 % higher than in latewood and the ratios were reversed for mannose (Panshin and De Zeeuw 1980). No difference was found between early wood and late wood for galactose, arabinose, and glucose in young trees. Analysis of successive growth increments within the tree in Pinus radiata D. Don showed a 3 % reduction of hemicelluloses from pith to bark and from the top to the butt of a tree. A maximum hemicelluloses content of about 11 % was found near the pith and toward the top of the tree. Glucose and mannose were shown to increases with age and decrease upwards while arabinose, xylose and galactose were shown to decrease with age and increased with height. Compression wood contains about 8-9 % more hemicelluloses than normal wood (Haygreen and Bowyer 2007).