18 BULLETIN 692, U. S. DEPAETMENT OF AGRICULTURE. 



greatly in seed of certain different kinds. The base of the seed has 

 a collarlike thickening, the callus, which sometimes bears a few 

 bristlelike white hairs. The apex of the seed is pointed and three 

 angled or four angled, depending upon the number of veins at the 

 apex of the lemma. 



The lemma has at least three evident longitudinal veins, one near 

 each margin, the marginal veins, and one in its center, the keel vein 

 (fig. 3, 1). These veins produce the 3-angled form of the apex 

 of the lemma. Often the keel vein does not develop to the apex of 

 the lemma, and it sometimes develops into a bristle, or awn, projecting 

 from the keel of the lemma (fig. 3,4)- In either event two additional 

 veins, the intermediate veins, appear between the keel and marginal 

 veins. The intermediate and marginal veins then give the apex of 

 the lemma a 4-angled form. The lemma is thin and usually 

 translucent at the apex, becoming thicker and opaque toward the 

 base. The translucent portion of the lemma gives the seed of some 

 species a silvery white appearance. 



The palet has two longitudinal veins if sufficiently well developed 

 (fig. 3, 2 and 3). It is very thin, often translucent and showing the 

 darker grain beneath, sometimes transparent and obscure. It 

 varies in size and texture and in its tendency to be free from or 

 adherent to the grain. 



The grain usually is reddish brown, oblong in outline, and finely 

 wrinkled at maturity. The interior, or endosperm, may be dry and 

 somewhat resistant to pressure on crushing, or it may be semifluid 

 and soft when crushed, depending on the species of the seed. 



DISTINGUISHING CHARACTERS. 



The distinguishing characters of the hulled seeds of redtop and 

 the other commercial bent grasses appear in the comparative size and 

 form of the seed, the texture and surface markings of the lenuna, the 

 character of the awn, the length of the palet compared with the length 

 of the lemma and of the grain, its texture and degree of adhesion to 

 or its freedom from the grain, the size and consistency of the grain, 

 the associated weed seeds and other seeds, and the character of the 

 chaff, if present. 



In practical seed analysis, smaU bulk samples of commercial seed 

 of redtop, Rhode Island bent, colonial bent, and South German 

 mixed bent can be distinguished one from another. The velvet- 

 bent seed in the South German mixed bent seed can be distinguished 

 and its true proportion determined. In mixtures of the commercial 

 kinds determination within 5 per cent of the true proportions of 

 redtop seed and seed of the fine bent grasses taken collectively can 

 be made. The seed of the fine bent grasses foimd in South German 

 mixed bent seed, exclusive of the velvet-bent seed it appears always 



