4 



SOUTH INDIAN GRASSES 



leaves of Panicum colonum. In Panicum fluitans the cells of the 

 upper epidermis bulge out so much as to form distinct papillae. 



The free surface of the epidermis is more or less cutinised in 

 the leaves of all grasses. In some leaves the cuticle is very thick 

 and even papillate as in the leaves of Aristida setacea and Panicum 

 repens whilst in others it is very thin, as in the leaves of Panicum 



Fig. 64. — Transverse section of a portion of the 

 leaf of Panicum colonum. x 120 



I. Motor cells ; 2. stomata; 3. sclerenchyma ; 4. chlorophyllous layer. 



colonum and P. fluitans. Cutinisation is rather prominent in the 

 leaves of grasses growing under dry conditions and it is less 

 pronounced in mesophytic grasses. 



I 10. 65. — Transverse section ot a portion of the 

 leaf of Panicum fluitans. x 120 



I. Motor cells ; 2. stomata; 3. sclerenchyma ; 4. chlorophyllous layer. 



As regards size, the epidermal cells overlying th.e sclerenchyma 

 are small and those lying over parenchyma are larger. Amongst 

 the larger cells some may be motor-cells. The stomata occur in 

 regular rows between the vascular bundles and they are quite 

 characteristic of grasses. They are more or less similar in structure 

 in all grasses. In the leaves of many grasses stomata are found in 

 both the upper and the lower epidermis and they are confined to 

 the lower epidermis in a few grasses only. 



The motor-cells vary very much both as regards their shape and 

 position. In some leaves as in the leaves of the grass Panicum 

 flaviclum the motor-cells are confined to the midrib on the upper 

 surface. 



