Origin and Development of Tissues in Root of Schizaea rupestris

Abstract

The structure is probably the simplest of all observed roots. All the tissues of the root have their origin in a pyramidal apical cell. The tissues are differentiated early; the initials of the epidermis, cortex, endodermis and peri-cycle are only one cell removed from the apical cell. The inner cortical layer and endodermis have a common origin; both are cortical. The pericycle and desmogen strand have a common origin; both are stelar. The arrangement of the bundle is diarch, consisting of 4 to 6 xylem cells and from 8-12 phloem cells. Thickening of the inner and radial walls of the "sclerotic layer" is a striking feature. Epidermal cells of root-hair destiny can be recognized very close to the apical region, and root hairs persist throughout the life of the root. The investigation supports Hanstein''s histogenetic idea of periblem and dermatogen.