44 



BULLETIN 1074, U. S. DEPARTMENT OF AGRICULTURE. 



When the dorsal portion is less keeled than normal the kernel is de- 

 scribed as flattened. Where only the tip of the kernel is thus flattened 

 it is described as having a flattened tip. 



The shape of the kernel has been used as a distinguishing char- 

 acter by only a few authors. Koernicke and Werner {133) recorded 

 the lengths and widths of the kernels and referred to some as round- 

 ish or elongated. Eriksson (88) used the number of kernels in 100 

 mm., placed side by side, to indicate the width of the kernel. This 

 character is, however, of value only in comparing varieties grown 

 under identical conditions. Heuze {112) described the shape of 

 kernels of each variety, using such terms as elongated, short, angu- 

 lar, compressed, ovoid, oblong, and swollen. Scofield (173) sug- 

 gested 16 descriptive terms to be applied to the shape of wheat 

 kernels. Wheat kernels can not be accurately described according 



to shape unless they are nearly normally 

 developed, that is, neither shrunken nor 

 excessively plump. 



GERM CHARACTERS. 



The size and shape of the germ or 

 embryo of the wheat kernel have seldom 

 been used as characters in classification. 

 After examining thousands of samples, 

 the writers have concluded that the size 

 of the germ is one of the most constant of 

 minor kernel characters. There is con- 

 siderable variation among the individual 

 kernels of a bulk sample, but typical kernels of a pure variety have a 

 characteristic size of germ. The germ is .developed earlier than the 

 endosperm and consequently is of almost normal size even in shrunken 

 grain. 



The germ is here described as small, midsized, or large. These are 

 shown in Figure 13. A small germ is one which occupies less than 

 one-sixth of the area of the dorsal surface of the kernel or the area 

 visible in dorsal view. A midsized germ occupies from one-sixth to 

 one- fourth of the dorsal area of the kernel. A large germ occupies 

 one-fourth or more of the dorsal area. 



The limits of the three size-groups overlap. Most kernels have a 

 midsized germ, so these characters are not much used in distinguish- 

 ing varieties. For some varieties, however, they could be used to 

 advantage by men in the grain trade. 



CREASE CHARACTERS. 



The crease or sulcus on the ventral side of the wheat kernel is 

 quite variable, but is of value in distinguishing a few varieties. The 



Fig. 13. — Germ sizes : a, Small ; h, 

 midsized; c, large. (Natural 

 size and enlarged 3 diameters.) 



