Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. It consists of cells, and the cell walls are composed of micro-fibrils of cellulose (40% – 50%) and hemicellulose (15% – 25%) impregnated with lignin (15% – 30%).
Along with hygroscopic, cellular, and anisotropic, how is the material of wood described?
{'text': 'heterogeneous', 'answer_start': 10}