12 



SOUTH INDIAN GRASSES 



The veins in the leaf-blade can usually be seen on holding the 

 leaf up to the light. All the veins run parallel. In most cases 

 the mid-rib is prominent and in some cases there may be also a 

 distinct keel. Amongst the veins running through the leaf-blade 

 some are large and prominent, while others are small and not 

 conspicuous. On account of this disparity, very often, ridges and 

 furrows become prominent on the upper or lower, or on both the 

 surfaces of the leaf-blades. Generally the two surfaces of the 

 leaf-blade are distinct, and they may be glabrous or hairy. In 

 most grasses the surfaces are rough or scabrid to the touch owing 

 to the presence of regular rows of exceedingly fine sharp pointed 

 minute hairs. 



The apex of the blade is generally sharp and pointed, acute or 

 acuminate, or sometimes it may be drawn to a very fine point by 

 gradual tapering. Blunt or obtuse tips are not altogether absent, 

 but it is not a common feature. The leaf-blades in Panicutn eolonum 

 and in some species of Andropogon are rounded or obtuse at the 

 apex. 



The margins of the leaf-blade are somewhat hyaline and they 

 may be perfectly even or cut into serrations of fine teeth in various 

 ways. (See fig. 15.) In addition to these minute teeth, there may 

 be long or short cilia. Sometimes the margins are glandular as in 

 Eragrostis Willdenoviana and Eragrostis major. 



The base of the leaf may be narrower, broader than, or about 

 the same as the breadth of the leaf-sheath. It may be rounded, 

 amplexicaul or narrowed. At the base and just above the ligular 

 region there will always be a white distinct zone in the lamina of 

 all grasses called the collar. This collar varies in length and 

 breadth according to the species of grass. 



In young shoots all the leaf-blades are usually found folded at 



the terminal portions. In most cases 

 the leaf-blade is rolled up inwards from 

 one end to the other so that one margin 

 is inside and the other outside. This 

 folding is termed convolute. This is 

 the kind of folding that is found in 

 most grasses. However, there are some 

 grasses such as Eleusine cegyptiaca and 

 Chloris barbata, in which the folding is 

 different. In these grasses the laminas 

 are folded fiat on their midribs so that 

 each half of the blade is folded flat on 

 the other, the inner surfaces being in 

 contact. The leaves are said to be 

 conduplicate in this case. When the 

 leaves are conduplicate the shoots are 

 more or less compressed. (See fig. 16.) 



Fig. 16. — Transverse section of 

 leaf-buds. 



A. Conduplicate ; I, 2 and 3. 

 leaf-sheaths; 4 and 5. leat-blades. 

 b. Convolute ; 1 and 2. leaf- 

 sheaths ; 3 and 4. leaf- blades. 



