10 



MASS. EXPERIMENT STATION BULLETIN 431 



Left; PIONEER 



Figure 8- Leaf Surface, 

 dull Right: 



Rancocas — glossy 



Figure 10. 



Papillose-hispid Conditian 



of Young Leaves. 



The presence or absence of pubescence, or 

 fine hairs, is often ver\ useful in distinguish- 

 ing varieties. On the upper surface of the 

 leaf, they are found along the midrib; on the 

 lower surface of the leaf, on the midrib and 

 sometimes also on the principal veins. Of 

 the four varieties having pubescence on both 

 surfaces of the leaf, Grover is out-=tanding 

 (Figure 9). The varieties Dunfee and Jersey 

 have no pubescence; that is. are glabrous, 

 while a number have pubescence on the 

 upper surface onlw Sometimes the pubes- 

 cence is carried down onto the petiole, or stem 

 of the leaf, so that its presence or absence 

 there helps in identification. 



The leaves of some varieties have short 

 thick hairs or bristles on their top surface. 

 This bristly, or hispid, condition occurs on 

 some of the young leaves of young plants of 

 certain varieties. The leaves which show 



