PLANTS OE THE INDIAN DESERT. 109 



anti-chorus and C. tridens and 1-3 seriate in G. abutilifolia. Wood 

 parenchyma is poorly developed. 



The wood in G. trilocularis is narrowed on one side, the narrowed 

 portion being characterised by a larger number of vessels and the 

 broader portion by more extensive wood prosenchyma. These 

 modifications in the structure of the wood may be the result of the 

 inclined nature of the axis, the narrowed portion being situated on 

 the lower side of the inclined axis. The abundance of wood pro- 

 senchyma on the upper side prevents the axis from bending. 



The pith is composed of thin-walled cells in species of Corchorus 

 and of thick-walled cells in species of Grewia. 



General Review : — There are a number of characters which can 

 be used for the diagnosis of the two genera. 



Corchorus: — Stomata with smaller epidermal cells on either 

 side of the guard-cells. Oxalate of lime in the form of clustered 

 crystals near the veins. Veins embedded and not provided with 

 bundle-sheaths. Clothing hairs unicellular. Outer walls of epider- 

 mal cells of the axis greatly thickened and cuticularised. Cortex 

 composed of three zones — outermost parenchyma, middle collenchyma 

 and innermost parenchyma. Pith composed of thin-walled cells. 



Grewia : — Stomata with ordinary epidermal cells on either side of 

 the guard-cells. Oxalate of lime in the form of solitary crystals. Veins 

 vertically transcurrent and provided with green bundle-sheaths. 

 Clothing hairs usually tufted. Epidermal cells of the axis uniformly 

 thickened on all sides. Cortex composed of three zones — outermost 

 cork, middle collenchyma, innermost parenchyma. Pith formed of 

 thick-walled cells. 



{To be continued.) 



