THE STEMS 



wheats (T. durum), usually have tall stems, while Small Spelt (T. mono- 

 coccum) and Bread wheats (T, vulgar e) are generally shorter, but tall and 

 more or less dwarf varieties occur among almost all the races of wheat. 

 The particular length attained is not only dependent upon the race or 

 variety of wheat, but also upon various external conditions. 



The application of nitrogenous manures increases the length of the 

 straw : phosphates and potash fertilisers tend to reduce it. 



Plants grown at wide intervals have taller stems than those which are 

 more crowded together, and the amount of moisture in the soil greatly 

 modifies the development of the straw. 



The lengths of the several internodes increase from the base to apex 

 of the straw, the uppermost internode being always the longest in plants 

 which have received no check in their growth. 



From measurements upon Rye and other cereals, Nowacki concluded 

 that the length of each internode upon a normally grown and fully de- 

 veloped straw is the arithmetic mean of the lengths of the internodes 

 immediately above and below it. It is possible to find individual stems 

 whose measurements closely approximate to this formula, especially 

 among short-strawed varieties of wheat, but Nowacki's law is not generally 

 true, neither in respect of the straws of an ordinary field crop nor of those 

 of plants grown a foot or more apart from each other. 



Below are given the average lengths of the internodes of long and 

 short straws of a variety of T. vulgar e and one of T. turgidum. 



AVERAGE LENGTHS OF INTERNODES (cm.) 



