Fig. 1.

Morphology of maize root growing through tight tubes with circular (A) or oval (B) cross sections. Arrows indicate the narrowest region of the tubes. Root tip in A is covered with mucilage (asterisk); schematic drawing in the left lower corner shows the real shape of the apex (root proper + root cap). In B the front (left) and the side (right) view of the same root are shown, and root buckling is indicated by asterisks. (C) Axial section of the maize root. The root-cap boundary is broken by the RAM cells growing onto the cap side (arrow). Scale bars: 0.5 mm (A), 1 mm (B), 50 μm (C).