The Formation of Adventitious Organs: IV. The Ontogeny of Shoots and Leaves From Epidermis Cells of Nautilocalyx lynchii

Abstract

Summary The epidermis of small expiants of Nautilocalyx leaves was observed microscopically during in vitro culture. The development of leaf primordia and adventitious shoots could be followed. Whole shoots could be traced back to 1–5 original epidermis cells, leaf primordia to 1–2 cells. Although all epidermis cells were capable of cell division, the meristems and shoots originated almost exclusively near hairs. Especially basal cells of glandular hairs seemed to play an important part in shoot formation. The exact location of the apical meristem of the shoot could not be recognized before a leaf primordium was formed. The apical area, i.e. the area between the first leaf primordia, could be traced back to a different number of original epidermis cells in different cases. The first leaf primordia and the apical area seemed to develop simultaneously into young leaves and a normally structured functional apical dome, respectively. Procambium strands were never found under the meristem before the bulging of the first leaf primordium. The possible role of the hairs in the orientation of the first leaves is discussed as well as the time of establishment of a new axis of symmetry for the adventitious shoot.