Page:The Journal of Indian Botany.djvu/604

164 THE JOURNAL OF INDIAN BOTANY. mal cells have outer walls thickened, granulated and convexely arch- ed outwards. Lateral walls are thin and straight. Primary cortex is composed of chlorenchyma. Collenchyma is developed in the ribs of P. Niruri.

Pericycle forms a loo?e ring of groups of bast fibres in P. Niruri, while E. granulata it is represented by isolated bast fibres. Wood forms a composite hollow cylinder with vessels distributed uniformly in incomplete rows in interfascicular wood prosenchyma. Vessels are more numerous in E. granulata. Medullery rays are uniseriate and numerous.

Pith consists of very thin-walled cells.

Asparagus racemosus Wilkl Var. javanica Bah. — Epider- mal cells with dark-brown granules. Cork subepidermal. Pericycle forming a composite ring of stone-cells. Vascular bundles scattered in a concentric fashion in the ground tissue. Ground tissue formed of cells with walls thin aud lignified.

Structure of the Axis. — The epidermis consists of tabular cells. Epidermal cells have outer walls a little thickened and are filled with dark-brown granules. Lateral walls are thin and straight. Cork is subepidermal and is formed of thin-walled cork cells. The pericycle forms a composite ring of stone-cells outermost layer of which con- sists of a little larger stone-cells with larger lumina. Vascular system consists of numerous bundles which are scattered in the ground tissue and are roughly arranged in rings. Bundles get smaller towards the periphery. The ground tissue is formed of cells with walls thin and lignified. The central portion of the ground tissue enclosed by the innermost ring of bundles consists of very thin-walled cells.

Commelina albescens Eassk. — Pigs. 296, 297. Epidermal cells of the leaf tabular, thin-walled and with outer walls flat. Stomata on both the surfaces and accompanied by subsidiary cells. Mesophyll of palisade tissue on the upper side and of arm-palisade tissue on the lower. Internal glands in the form of cells with tanniniferous contents. Bundles of acicular raphides in lower epidermal cells. Clothing hairs on the leaf in the form of uniseriate bracket-shaped trichomes. Pericycle forming a composite ring of stone-cells. Collenchyma subepidermal. Assimilatory tissue lacunar Vascular bundles apposed to the stone-tissue of pericycle. Numerous isolated secretory receptacles surrounded by parenchyma in the ground tissue.