Xylan

noun

1. A yellow, water-soluble, gummy polysaccharide found in plant cell walls and yielding xylose upon hydrolysis.
2. A gelasinous, levorotatory compound, C5H8-O4(?), contained in all kinds of wood. With sulphuric acid it yields the sugar xylose; boiling mineral acids convert it chiefly into fur-furaldehyde. It is also called wood-gum.
3. A gummy substance of the pentosan class, present in woody tissue, and yielding xylose on hydrolysis; wood gum.
4. A polysaccharide, consisting of xylose residues, found in the cell walls of some algae and plants.