44 



Group V. Acute-sheathed Grasses. Page 52. 

 The sheaths of most grasses are round. In a few 

 species, however, the blades are folded and the sheaths 

 are more or less flattened. If the flat (or angular) 

 sheath has acute edges, the grass belongs to this 

 group. All have entire sheaths and folded blades, 

 except Melica. 



Group VI. Net-sheathed Grasses. Page 53. 

 vi. 15 In the blades, and more especially in the sheaths of 

 certain grasses, mainly aquatics , large chambers con- 

 taining air are present. The presence of these 

 chambers gives a netted appearance, by transmitted 

 light, to the part in which they are present. This 

 netted structure is the characteristic of the group. 



Group VII. Bitter-tasted Grasses. Page 55. 

 Cumarin is the principle which gives the char- 

 acteristic taste. It is volatile, and odoriferous ; the 

 odour of new mown hay, woodruff, &c., depends on 

 its presence. Other grasses, such as false oat, may 

 have a bitter taste ; this is not due to cumarin, but to 

 some other substance. Grasses which contain curnurin 

 are alone included in this group ; its presence is recog- 

 nised by chewing the blade. 



Group VIII. Bristle-bladed Grasses. Page 55. 

 vni. 2 . The bristle-like (setaceous) blade is a leaf adaptation 

 for reducing the evaporative surface of the plant. 

 Hairiness, hardness, and wax-coxered surfaces 

 (glaucous) are other contrivances for the same purpose, 



