96 THE JOURNAL OF INDIAN BOTANY. 



senchyma. Wood parenchyma developed on the inner side of the 

 xylem bundles. Medullary rays absent. Pith of thin-walled cells. 



Structure of the Leaf. — The epidermis consists of polygonal cells 

 in B. patula, B. hochstetteri and J. simplex or of tabular cells as in 

 B. sindica. The outer walls are thickened, thickening being consi- 

 derable in B. sindica. Tne outer walls are convexly arched outwards 

 and the lateral walls thin and undulated in J. simplex. The cells are 

 uniformly thickened on all sides in B. patula and B. hochstetteri ; the 

 lateral walls are undulated. The lateral and inner walls are also 

 thickened in B. sindica and the latter are undulated. 



Numerous large rounded cells are intercalated amongst ordinary 

 epidermal cells ; and each contains a spherical cystolith (fig. 258), 

 The stomata are accompanied by subsidiary cells. The guard-cells are 

 usually elevated and the front cavity is on a level with the surface in 

 all members except B. hochstetteri in which the guard-cells are in the 

 plane of surrounding cells and the front cavity is a little depressed. 

 The stomata are more numerous on the lower surface except in 

 B. sindica where they are more numerous on the upper surface. This 

 may be accounted for by the occurrence of subepidermal aqueous 

 tissue on the lower side where there should be as few stomata as possi- 

 ble to economise the supply of water contained in the aqueous tissue. 

 The mesophyll is isobilateral except in B. patula in which it consists 

 of palisade tissue on the adaxial side and of arm-palisade tissue on the 

 abaxial side. In B. sindica there is palisade tissue on the adaxial side 

 and subepidermal aqueous tissue and palisade tissue on the abaxial 

 side. 



In B- hochstetteri and J. simplex there are peculiar structures on 

 both sides of the mesophyll. They are at some places circular in 

 section and are composed of irregular cells faintly green in colour ; at 

 other places they have the form of secretory cavities with bounding 

 cells projecting into them (fig. 258). These structures probably 

 represent the internal secretory organs. Oxalate of lime does not 

 occur in the form of crystal sand in the cell-cavity of clothing hair8 

 on the leaf and in the epidermal cells of the axis of B. sindica. The 

 veins are embedded and are not enclosed in bundle-sheaths. 



The hairy covering on the leaf and axis consists of clothing and 

 glandular hairs. The clothing hairs in B. patula (fig. 251) and 

 J. simplex (fig. 258) are simple uniseriate trichomes with thickened and 

 muriculate walls ; the constituent cells in the former are dilated at 

 the lower end and give a jointed appearance to the trichomes. In 

 B. hochstetteri there are unicellular elliptical hair-like structures with 

 walls thickened and muriculate on the leaf ; on the axis, besides the 

 long simple uniseriate trichomes (fig. 255), there are other special 



