EXPLANATION OF FORM. 15 



fit around the flowering glume. Plate IV, fig. 2, shows a spikelet with 

 narrow outer glume, while in Plate V, fig. 19, the glumes on the com- 

 pound spikelet are relatively broad. The terms long, medium, and 

 short apply to the relative length of this outer or flowerless glume. 

 The spikelet in Plate IV, fig. 2, has short outer glumes, while the 

 spikelet in fig. 1 has long glumes; that is, glumes nearly or quite as 

 long as the flowering glumes. 



The terms firm,, medium, and weak under attachment have to do with 

 the firmness of the attachment of the glumes, when ripe, to the rachilla 

 upon which they are borne. This firmness of attachment indicates the 

 ability of the glumes to retain the grain after the plant reaches maturity. 



The keel of the outer glume is the pronounced central nerve and 

 may be broad, medium, or narrow. Varieties of Triticum durum are 

 characterized by the broad keel (PI. VII, fig. 1) which is prominent 

 throughout its entire length. The keel is always present, but may not 

 be distinct in some varieties of Triticum osstvoum,. 



The beak of the outer glume is the tip of the keel. It may be either 

 long (PI. VI, figs. and 7). medium (fig. 5), or short (figs. 1 and 2), and 

 acute or blunt. 



The shoulder of the outer glume is that portion on either side of the 

 midrib at the tip of the glume and it may be either broad (PI. VI, fig. 

 2), medium (fig. 1), or narrow (fig. 5), and square (PI. VII, fig. 5), 

 sloping (fig. 1), or round (fig. 6). 



The auricle of the outer glume (PI. VII, fig. 5) occurs, when present, 

 at the tip of the shoulder, which is sometimes extended into a distinct 

 ear. It may be sharp (PI. VI, fig. 4), medium, blunt (fig. 1), or want- 

 ing (fig. 3). 



The auricle notch (PI. VII, fig. 5) is the notch in the tip of the outer 

 glume between the auricle and the beak. It may be deep (PI. VI, 

 fig. 1), medium, shallow (fig. 7), or wanting (fig. 5). 



The apical glumes are the outer glumes of the apical spikelet, and 

 they sometimes show distinct differences. Two types of these outer 

 glumes, of which there are but two on each spike, are shown in Plate 

 VII, figs. 2 and 3. These glumes may be keeled or not keeled, notched 

 or rounded, and they may be similar or dissimilar. 



Grain. — The terms very hard, hard, medium, soft, and very soft are 

 only comparative, but are convenient in distinguishing between differ- 

 ent sorts of grain. 



The size is determined by weighing 100 average seeds. This determi- 

 nation should be made in duplicate, at least. 



The terms long, medium,, and short, applying to the shape of the grain, 

 are only comparative. They apply to the relative length and diameter 

 of the grain. Extreme types are shown in Plate V. The grain may 

 also be either curved (fig. 4), straight (fig. 6), or pear shaped (rig. 8). 

 The pear-shaped grain is the kind sometimes known as club wheat. 



