From the macroscopic to the molecular scale. The cellulose hierarchical architecture studied in wheat awns, revealed new data on the hygroscopic mechanism of seed dispersal. Wheat awns bend as they dry (panel A to B). Cross section images taken by a variety of microscopic tools of the bending region (red square in panel B). (C) Scanning electron micrograph (SEM) shows the hygroscopically-active (contracting) region, which is the narrow upper part of the cross section (scale: 200 µm). See the pointy silica hairs that allow the awn to slide only in one direction. (D) A close up (by SEM) of a cell from the awn's active region, illustrating the cell wall plywood structure (scale: 10 µm). (E) Bright-field and (F) polarized-light images (both acquired by light-microscopy) of a cross section of the active region (scale: 100 µm). Close up (by polarized light microscopy) of cells from the edge (G) and the center (H) of the active region shows variation in the cellulose micro-fibril angles (scale: 10 µm). (I and J) Raman images (88 mm x 70 mm) of similar cells demonstrates that there is no variation in the cellulose concentration.