6 4 



THE WHEAT PLANT 



The diameter of the straw is influenced by the same numerous factors 

 as those which affect the length ; especially stout stems are generally 

 found on plants which are grown at wider intervals than one foot apart. 



The average diameter of the separate internodes increases from below 

 up to the fifth ; the sixth or upper internode is more slender than the 

 rest. Each individual internode is thickest in the middle, from which 

 point it tapers more or less evenly to both ends. 



The average thickness of the wall of the straw decreases from the base 

 to the apex ; similarly, the thickness of the wall of each internode is 

 greatest at the base and diminishes gradually from below upwards. 



The following are measurements of the diameters of the internodes, 

 the thickness of the wall, and thickness of the zone of hypoderm of hollow 

 straws of T. vulgar e (Squarehead) taken from an ordinary field crop. 



' TILLERING " 



The primary stem of the wheat embryo within the grain is extremely 

 short, and consists of hypocotyl, or portion below the point of insertion 

 of the scutellum, and the epicotyl, or axis of the plumule. 



When growth commences in grains sown in the ordinary way in the 

 field, the hypocotyl remains short, but the lower part of the epicotyl 



