An Endodermal Phellogen in the Stem of Paederia foetida Linn

Abstract

DURING the course of an anatomical study of Pœderia fœtida, a twining shrub of these parts, belonging to the family Rubiaceae, we found that the phellogen originates in the stem, not in the subepidermal layers of the cortex as in most dicotyledons, but in the endodermis. We have seen this in a large number of sections, cut free-hand as well as on the microtome, from various collections of the material made at Dacca. The endodermis itself is a clear and unmistakable layer easily recognized by the presence of the Caspary bands on its radial walls and forming a continuous cylinder enclosing the stelar tissues. After the first tangential division of its cells the inner layer functions as the phellogen, and the outer, together with the whole of the cortex and the epidermis, is sloughed off as cork formation advances. We would like to know if a similar condition has been noticed in any other plant and what may be the causal factors leading to it. This observation is recorded here in the hope that it will attract the attention of other plant anatomists.