The Araf residue on grass GAX or AX may be further decorated by additional β-1,2-linked Xylp or α-1,3-linked Araf substituents (Faik 2010). Moreover, feruloyl substituents are present on the C-5 position of the Araf sidechains covalently linking xylans to lignin polymers in grasses (Faik 2010).