KEY TO COMMEKCIAL SEEDS. 19 



KEY TO COMMERCIAL BLUEGRAS8 SEEDS AFTER PREPARATION FOR 



MARKET. 



Seeds 4-(3 »""• long; web longer than glume, forming a woolly tuft and causing the 



seeds to cling in bunches in the sample P. arachnifera. 



Seeds 2-2| mm. long, usually rubbed free from hairs and disconnected in the sample, 

 often tnore or less torn at the apex; commonest commercial kinds. 

 Intermediate veins distinct; seeds contracted at the apex and not wider (dxnr than 

 below the middle; hyaline margin of apex seldom present in rubbed seed. 



P. pratensis. 

 Intermediate veins very indistinct; seeds broader above than below the middle; hyaline 



margin of apex usually evident and faring P. compressa. 



Seeds 2-3 mm. long, chiefly unrubbed; disconnected or clinging somewhat in the 



sample; usually not torn at the apex; smooth or the pubescence on the veins 



and the web more or less evident. 



Intermediate veins indistinct. 



Rachilla segment usualli/ pubescent; long, sterile rachilla segments conspicuously 



common; intermediate veins scarcely evident; keel and marginal veins pubescent; 



apex of seed often flaring; seed 2^-3 mm. long P. neinoralis. 



Rachilla segnient smootit; intermediate veins but slightly evident; keel and marginal 



veins pubescent; apex of seed sometimes flaring; seed 2-2\ mm. long. P.trijlora. 



Intermediate veins very distinct. 



Rachilla segment smooth and slender; keel pubescent, marginal veins usually 



smooth; apex of seed acute and compressed; seeds often distinctly curved as 



viewed from the side , p. trivialis. 



