Page:The Journal of Indian Botany.djvu/323

 THE

Journal of Indian Botany*

Vol. I. MAY, 1920. Nos. 9 & 10.

THE PHYSIOLOGICAL ANATOMY OF THE PLANTS OF THE INDIAN DESERT

BY

T. S. Sabnis, B.A., M.Sc

St. Xavier's College, Bombay. t (Continued from p. 2i7.)

The mesophyll is composed of palisade tissue on the upper side and of arm-palisade tissue on the lower. Internal secretory organs are not found. Oxalate of lime occurs in the form of clustered crystals near the veins in A. desertorum.

The veins are embedded and are enclosed in green bundle- sheaths.

Hairy covering is found on the axis and on bhe upper surface of the leaf of A. desertorum and consists of unicellular conical hairs with verrucose walls and sometimes seated on a group of two or three epidermal cells (fig. 126). Glandular hairs are not found.

Structure of the Axis : — The epidermis is composed of tabular cells with outer walls thickened, verrucose and convexly arched out- wards. The inner walls are thickened; and the lateral walls are thin and straight. The axis is ribbed at the angles. The cortex is composed of chlorenubyma extending to the ribs.

The pericycle forms a loose ring of bast fibres, those in A. bacci/era having thin walls and large lumina. The wood is composite. The vessels are uniformly distributed in incomplete rows, vessels becoming larger towards the inner margin of the wood. The interfascicular wood prosenchyma is composed of cells with thin walls and large lumina and is more extensive in the upper half. The medullary rays are uniseriate and numerous. Wood parenchyma is abundantly developed at the inner margin of the wood cylinder.