17 



SOUTH INDIAN GRASSES 



In order to give a general idea of the variations in the structure 

 of the stem in grasses a few examples are chosen and the details 

 of the structure of the stems of these grasses are dealt with here. 



Flo. 26. --Transverse section of a portion of the stem of Pennisetum cenchroides. * 70 

 1. Epidermis: 2. sclereiv-hvmi : 3. vascular handle. 



The stem of Pennisetum cenchroides is somewhat round in outline 

 in the transverse section with a slight curvature in the front. The 

 vascular bundles are rather numerous and irregularly scattered all 



over the ground tissue. The 

 peripheral bundles are not so 

 close to the periphery of the stem 

 as in Rottboellia exaltata. These 

 are separated from the epidermis 

 by several layers of parenchy- 

 matous cells. Further these peri- 

 pheral bundles are all imbedded 

 in a continuous sclerenchymatous 

 band which runs round the stem 

 in the form of a ring. The 

 epidermal cells as well as the 

 layer of cells in immediate 

 contact with it are thick-walled. 

 In the vascular bundles of the 

 ground tissue the bundle-sheath 

 is rather prominent and the 

 phloem portion is well developed. 

 (See figs. 25 and 26.) 

 In the stem of Eriochloa polys tachya, all the vascular bundles 

 are more or less peripheral in position leaving a wide area of 

 parenchymatous cells in the centre. The outline of the stem in 

 cross section is rotund or ovate-rotund with the front side some- 

 what flattened and straight. The epidermal cells alone are 



FlG. 27. Transverse section of the stem 

 of Eriochloa polysiachya. x 25 



