a chain of β(1→4) linked xylose residues with a variety of side chains (Fig. 3). The xylan backbone in dicot species is decorated with α(1→2)linked glucuronic acid (GlcA) and 4-O-methyl-glucuronic acid (MeGlcA). This type of xylan is known as glucuronoxylan (GX) (Fig. 3B). Xylan in monocots on the other hand is glucuronoarabinoxylan (GAX), where the substituents are α(1→3)- and/or α(1→2)-linked arabinofuranosyl (Araf) and α(1→2)-linked GlcA/MeGlcA units (Fig. 3C).