Leaf and Stem Heteroblasty in Zea

Abstract

Although leaf heteroblasty is common, its documentation for grasses is rare. Leaf-shape and internode-shape changes along the stem of 4 cultivars [Oh43, A632, B14A and W23] of mature Z. mays plants were studied. The data, presented as double-log plots of leaf length vs. leaf width of successive leaves along the stem, document the general heteroblastic condition, but reveal that the exact dimensions of such changes are cultivar related. The double-log plots of measurement from samples of ''Oh43'' are similar but possess recognizable differences to similar plots from ''A632'' and other cultivars. From the measurements of shoot apical meristems, the inflecting changes in leaf shape along the stem are not based on comparable inflecting changes in meristem width or length during leaf initiation. During the leaf-initiating period, the meristem grows steadily in height and width prior to the changes associated with tassel initiation.