Morphological characterization of maize ps1 mutant plants. A, Wild type (WT) plant at 60 d after planting segregated from ps1 × HN17 BC3F2. B, ps1 mutant plant at 60 d after planting segregated from ps1 × HN17 BC3F2. C, Near-ground stems of wild-type (left) and ps1 mutant (right) plants. The arrowhead indicates the curved node of the ps1 mutant plant. D to I, Scanning electron micrographs of longitudinal sections of the third aboveground node in wild-type (D–F) and ps1 (G–I) mutant (the curved node) plants. D and F show enlarged views of the left and right sides of E, respectively; and G and I show enlarged views of the left and right sides of H, respectively. J, Longitudinal cell numbers of the left and right sides of the third node in wild-type plants and ps1 mutants. Values are means of at least three plant measurements. For the curved node in ps1, the left and right sides refer to the far- and near-ground sides of the node, respectively. Asterisks indicates a significant difference, as indicated by P < 0.05 in Student’s t test; error bars represent the sd.