CHAPTER 11. 



THE VEGETATIVE ORGANS (continued). 



The leaves of all our grasses consist of the blade, 

 which passes directly into the sheath, without any petiole 

 or leaf-stalk (Fig. 1). 



The sheath is usually obviously split, and so rolled 

 round the internode that one edge overlaps the other, 

 but in the following grasses the sheath is either quite 

 entire, or only slit a short way down, the two edges being 

 fused as it were for the gi-eater part of its length. 



Sheath more or less entire. 



Ghjceria aqimtica and O. Jluitans. 



Melica unijlora and M. nutans. 



Dactylis glomerata. 



Poa trivialis (Fig. 8), F. pratensis, P. alpina. 



Seshria ccerulea. 



Bromus (all the sixjcies). 



Driza media and B. minor. 



In some cases — e.g. Arrhenatherum, Bromus asper, and 

 Holcus lanatus — the sheath is marked with a more or less 

 w. 2 



