160 THE WHEAT PLANT 



Young Tillered Plant. Habit of shoots, erect, sloping, or prostrate ; 

 colour of the leaves ; leaf-surface, glabrous or pubescent, and distribution 

 of the hairs on the longitudinal ridges. 



Straw. Its average height ; whether hollow or solid, rough or 

 smooth. 



In the description of wheats given later I have adopted the following 

 general table of straw lengths : 



Very short . . . Below 24 in. 



Short .... 24-34 m - 



Medium . . . 34-44 ,, 



Tall . 44-54 



Very tall . . . Over 54 in. 



Ear. Average length ; breadth across the face and width of the two- 

 ranked side : whether specially glaucous or non-glaucous and yellowish- 

 green. In awned forms the length of the awns ; in beardless forms 

 whether " tip-bearded " or truly awnless. 



The general form, whether uniform in diameter, clubbed at the apex, 

 or tapered either from base upward, or from middle upward and down- 

 ward. 



Ear " density " and number of spikelets. 



It is usual to define the " density " (D) of an ear as the number of 

 spikelets per 10 cm. length of the rachis. The total length in centimetres 

 (L) of 10 normally developed ears is measured and the number of spikelets 

 (N) counted ; from these determinations the density is calculated thus : 



N x 10 

 L 



In the descriptions of wheats given later the following table of densities 

 is adopted : 



Lax . . . . D below 22. 

 Medium . . . 22-28. 



Dense .... 28-34. 

 Very dense . . . above 34. 



Very dense ears are characteristic of the Club Wheats ; a few are seen 

 in the Bread Wheats, but they are rare among the Macaroni and Rivet 

 Wheats and unknown in Emmer and Large or Small Spelt. 



The density of the ear is subject to the ordinary fluctuating variation 

 and is influenced to some extent by climatic changes and alterations in the 

 water-supply and nutrition of the plant. 



The application of large amounts of nitrogenous fertilisers tends to 

 lengthen the internodes of the rachis, but I have failed to produce by the 

 most drastic manurial treatment a lax ear in plants of T. compactum or 

 in any Squarehead vulgare wheat. 



