^6 Bulletin VII. 1. 



these are the outer or empty glumes. The axis to which these 

 "flumes are attached is termed the rachilia, and between each 

 flower and this rachilia there is usually a two-nerved bract, the 

 palea, the prophyllura to the floral branch. In one- flowered spike- 

 lets where there is no extension or prolongation of the rachilia, this 

 palea is apparently opposite the flowering glume. The lower pair of 

 glumes — the empty ones — often differ from each other in size or 

 length, and sometimes, though rarely, one or both are absent. 

 The glumes may be awned or "bearded," or awnless; they may 

 be sharp-pointed, obtuse or toothed at the apex; they may be 

 nerveless or one to many-nerved. As to other variations it is 

 necessary to refer the reader to the larger descriptive works on 

 botany. 



The arrangement of the spikelets upon the stem constitutes 

 what is termed the inflorescence, or what we often hear erroneously 

 called the "head." If that portion of the main axis or stem which 

 bears the spikelets is unbranched so that these are sessile (i.e., 

 without pedicels), the inflorescence is a spike, as in wheat or rye- 

 grass; when the main axis is branched, each branch forming a 

 pedicel to a single spikelet, the inflorescence is a raceme. This form 

 is not common. Usually the primary branches branch again and 

 again, resulting in the formation of 3. panicle. The panicle may be 

 open or widely spreading, as in oats or in Kentucky blue-grass; 

 or, if the branches are very short, it may be narrow and spike-like, 

 as in timothy or in meadow fox-tail. All gradations of form 

 between these two extremes occur. 



Number of Species. — There are about thirty-flve hundred known 

 species of grasses, varying in size from the moss-like Coleanthus 

 of the North to the tree-like bamboos of the tropics, which tower 

 to the height of a hundred feet or more; and ranging in distribu- 

 tion from Kerguelen Land on the South to the extreme limit of 

 vegetation beyand the arctic circle. There is no order of plants 

 more widely distributed, existing under the greatest diversity of 

 soil and climate, and no order presents such a vast number of in- 

 dividual plants or is so important and directly useful to man. 



Uses. — When we consider that rice, wheat, corn, oats, barley, rye, 

 sorghum, and the millets, sugar-cane and the bamboos are all true 

 grasses, and further that these plants furnish the bulk of the hay 

 crop and pasturage of the temperate regions, we can hardly realize, 

 much less definitely estimate, the great importance of the Gram- 

 inece, or form any just conception of the part these plants play in 

 our individual and national economy. The fact of the vast im- 

 portance of the order may be very forcibly presented by trying to 

 picture the result upon the human race, if by chance all these 

 food and forage plants were at once destroyed. 



I 



