28 



SOUTH INDIAN GRASSES 



interrupta has more or less the same structure, but the cortex has air 

 spaces here and there. Other minor differences may be seen on 

 referring to figs. 35 and 36. 



The stems of grasses growing in wet or marshy situations differ 

 in structure from those detailed above. As examples the stems of 

 Panicum flavidum, Panicum colonum, Panicum Cnis-galli and Panicum 

 fluitans may be considered. The stem of Panicum flavidum is 



Fig. 39. — Transverse section of a portion of the stem of Panicum colonum. x yo 

 I. Epidermis; 2. sclerenchyma ; 3. vascular bundle. 



broadly ovate in cross section with a flat front and is more or less 

 solid, though occasionally the parenchymatous cells in the centre 

 get broken. Two rows of vascular bundles surround a fairly large 

 amount of parenchymatous cells of the ground tissue. There is a 

 continuous ring of sclerenchyma separated from the epidermis by 

 a fairly broad cortex. The cortex has a number of fairly large air- 

 cavities separated by bands of parenchymatous cells. Within the 

 sclerenchymatous band lie small vascular bundles at regular inter- 

 vals just towards the cortex. A few isolated bundles are in contact 

 with the inner border. (See figs. 37 and 38.) 



The stems of Panicum colonum, Panicum stagninum and Panicum 

 Crus-galli have in their centre in the ground tissue stellate cells 

 with air-cavities. This part is surrounded by a fairly broad 

 portion of parenchymatous cells in which are imbedded two rows 



