192 THE JOUKNAL OF INDIAN BOTANY. 



Clothing as well as glandular hairs do not occur on the leaf and 

 axis. The absence of a hairy covering is compensated for partly by 

 the palisade-like elongated epidermal cells and partly by the two- 

 layered epidermis. 



Structure of the Axis. — The epidermis consists of small tabular 

 cells with outer walls thickened. The cortex is composed on its outer 

 side of an extensive cork tissue and on its inner side of glandular 

 tissue already described (fig. 87). 



The pericycle is composed of closely placed large groups of stone- 

 cells separated by secretory cells with tanniniferous contents. The 

 wood is composite (fig. 87). Vessels are fairly large and numerous. 

 Interfascicular wood prosenchyma is composed of thin-walled cells 

 with small lumina. The medullary rays are 1-2 seriate and are 

 numerous, some of their cells holding tanniniferous contents. 



The pith is heterogenous and is composed of groups of large 

 elongated cells surrounding small cells (fig. 87). 



RHAMNEAE. 



Zizyphus jlljuba Lam. — Fig 88. Epidermis composed of hori- 

 zontally tabular cells. Upper epidermis of the mid-rib grooved. 

 Uniseriate trichomes more numerous on the lower surface. Secretory 

 cavities not found in cortex. Pericycle formed of stone-cells. Long 

 thin groups of stone-cells present in soft bast. 



Zizyphus trinervia Boxb — Figs. 89, 90. Epidermis of the 

 leaf composed of cubical or vertically tabular cells. Upper epidermis 

 of the mid-rib not grooved. Uniseriate trichomes absent on the upper 

 surface. Secretory cavities numerous in the cortex. Long thin groups 

 of stone-cells found in soft bast. Perioycle formed of bast fibres. 



Zizyphus rotundifolia Lam.— Figs. 91, 92. Epidermis of the 

 leaf formed of cubical and vertically tabular cells. Upper epidermis 

 of the mid-rib grooved. Uniseriate trichomes more numerous on the 

 lower epidermis. Secretory cavities wanting in cortex. Stone-cells 

 absent in soft bast. Pericycle formed of bast fibres. 



Zizyphus truncata Blatt. and Hall. — Figs. 93, 94. Upper 

 epidermis consisting of cubical and vertically tabular cells. Upper 

 epidermis of the mid-rib not grooved. Uniseriate trichomes absent 

 on the upper surface. Secretory cavities occurring in cortex. Stone- 

 cells wanting in soft bast. Pericycle formed of bast fibres. 



Structure of the Leaf: — The epidermis of the two surfaces differ 

 in structure. The upper surface is smooth while the lower one is 

 characterised by alternate ridges and furrows. The epidermal cells of 

 the upper surface are larger and cubical or vertically tabular in all 

 members (figs. 91, 93,) except Z. jiijuba where they are mostly 



