Observations on pre-prophase bands of microtubules in uniseriate hairs, stomatal complexes of sugar cane, and Cyperus root meristems.

Three aspects of the location and properties of pre-prophase bands of microtubules inplant tissues were examined. (i) Anatomical locations: Pre-prophase bands were found preceding mitosis in the basal meristematic cell of uniseriate hairs in Salvinia auriculata and in intercalary dividing cells in the uniseriate hairs of Tradescantia stamens. Previously they had only been found in 2- or 3-dimensional aggregates of cells. Other new locations were Tradescantia stamen filaments, and periclinal and anticlinal divisions in root and root cap meristems of Cuperus eragrostis. (ii) Prediction of the site of cytokinesis: Developing stomatal complexes of Saccharum officinarum were examined in view of recent reports that guard mother cells in this plant violate the otherwise general rule that the pre-prophase band predicts the line of fusion of the cell plate and the parental wall. The generality of the prediction phenomenon was upheld. (iii) Bisection of pre-prophase band sites: Evidence that the site of the pre-prophase band in the cell cortex is (at least approximately) bisected at cytokinesis was obtained for asymmetrical divisions in Cyperus roots, stomatal complexes of Saccharum, and Salvinia hairs, and symmetrical divisions in Tradescantia stamen hairs and Saccharum guard mother cells. The observations are discussed with particular reference to possible roles of the pre-prophase band site after its microtubules have disappeared at prophase.