390 LEAF-ANATOMY OP THE GENUS AXDROPOGON, 



its extent. The extreme development of sclerenchymatous tissue 

 results in the elimination of many of the chlorophyll-bearing 

 cells, so that the latter are only few in number. 



All the primary bundles have the sclerenchyma well developed, 

 and in direct contact with the phloem- and xylem-tissue. It does 

 not, however, surround the phloem- and xylem-tissue as in the 

 case of the primary bundle; and, consequently, the chlorophyll- 

 bearing cells aie more numerous and more regular in size than 

 in the case of that bundle. The intermediate bundles are com- 

 pletely sumjunded by chlorophyll-bearing parenchyma, but the 

 sclerenchyma is extremely well developed on the inferior surface, 

 and projects well beyond the level of the epidermis. 



The epidermal cells on the inferior surface are uniform in size. 

 Over many of the primary and intermediate bundles, they become 

 more or less lignified, and take on the character of sclerenchyma- 

 cells. Between the masses of sclerenchyma mentioned above, 

 the epidermal cells are arranged in grooves. In some cases, the 

 apical cell of the conical masses of projecting sclerenchyma is 

 extremely large. Throughout the whole of the inferior surface, 

 the epidermal cells are protected by an extremely thin cuticle. 

 The epidermal cells on the superior surface take on the character 

 of bulliform cells. These are noteworthy inasmuch as they form 

 a double row of cells, the bottom row being much larger than 

 that above. These cells extend throughout the whole space 

 between the primary bundles, and have not the fan-shaped char- 

 acteristics present in the other species. The stomata are numerous 

 on the inferior face, and, in most cases, are sunk in the epidermal 

 grooves between the masses of sclerenchymatous tissue. A few 

 stomata may be seen on the superior face, but they are not as 

 plentiful as in the other species. 



Andropogon bombycinus R.Br. (Plate xxxiii.). 



The anatomical structure of a leaf closely resembles that of A. 

 rffractus. The principal points of difference are : — 



(1.) The number of secondary bundles is smaller. 



(2.) The sclerenchymatous masses developed under the primary 

 and intermediate bundles are larger. 



