BOTANICAL CHARACTERS 121 



The shape of the grain varies greatly (Fig. 61). In most CHAP, 

 breeds it is flattened and more or less wedge-shaped, with an IV ' 

 indented apex (Dent maize) ; in one variety it is spheroidal 

 or conical (Flint maize) ; in Pop maize it is distinctly and 

 sharply beaked ; in Sugar maize, when dry, the grain is much 

 wrinkled owing to absence of starchy endosperm. 



Depth and Breadth of Grain. 



The depth (or length) of the grain varies greatly, and is said 

 to be a quite constant character in different breeds. Breadth 

 and thickness of grain, on the other hand, are not considered 

 so constant. 



Each of the five cultural varieties of maize (Pop, Flint, 

 Dent, Flour, and Sugar) contains three well-defined sub-types, 

 based on the relative breadth and depth of the grain. Thus : — 



Group A — Grain broader than deep. 

 Group B — Grain as broad as deep. 

 Group C — Grain much deeper than broad. 



According to Sturtevant (2) these depend on climatic con- 

 ditions ; the A group grows in short-season climates, the C 

 group in long-season climates, while the B group is inter- 

 mediate. A climate suitable for the C group will, naturally, 

 also suit the other two groups, but they may not prove as 

 profitable, and would therefore be less desirable. Deep grain 

 appears, therefore, to indicate a long growing season, and 

 vice versa ; if this is constant, one should be careful not to 

 select seed-maize having too deep a grain to suit the particular 

 altitude or rainfall. 



Shape of Grain. 



(a) If broad above, tapering to a slender base with straight sides, the grain 



is described as straight cuneate. 

 [V] If the same general shape, but with rounded edges, it is curved 



cuneate. 



(c) Broad above, narrower below, connected by straight lines, truncate 



cuneate. 



(d) Long and uniformly narrow above, only tapering to a more or less broad 



base, shoe-peg form. 



(e) Short, and as broad at base as at summit, rectangular. 



{f) Slightly rounded at corners, both above and below, round-cornered. 



