EXPERIMENTS WITH DURUM WHEAT. 9 



of other wheats. Production was reduced again during the years 

 1913 and 1914. This smaller production was responsible in part for 

 the higher price which was obtained for the crop during these years. 

 In 1915 production increased sharply in response to the stimulus of 

 good prices and increasing demand. Since the fall of 1911, as noted 

 previously, the price of durum wheat usually has been equal to or 

 slightly better than that obtained for common spring wheats. (See 

 fig. 1.) Several causes have contributed to this. Among them are 

 (1) better facilities for mining these hard wheats, (2) increasing use 

 for making macaroni in this country, and (3) increasing export de- 

 mand. Figure 3 is a map showing the production of durum wheat 

 in Minnesota, South Dakota, North Dakota, and Montana in 1915, 

 according to the figures of the Bureau of Crop Estimates. 



DESCRIPTION AND KEY. 



In the genus Triticum, durum wheat has been regarded as one of the 

 seven or eight species or subspecies. The writers are not concerned 

 with its taxonomic status at this time, but merely with those char- 

 acters which mark the durum wheats as distinct from the common 

 wheats. 



DESCRIPTION. 



Durum wheat differs from common wheat in the characters of both 

 plant and kernel. The durum plant usually is taller (fig. 4) and more 

 vigorous than that of common wheat varieties; the culms are thicker 

 and the leaves broader. The spikes average broader and shorter (see 

 fig. 9) than those of common wheat and are much more compact. In 

 some varieties they are so short and broad as to be veritable club 

 wheats. 



The crowding of the spikelets on the rachis, together with the large 

 size of the kernel, results in a characteristic outcurving or expansion 

 of the spikelet which widens the spike on both sides of the rachis. As 

 a result, the spike is flattened transversely to the plane of the rachis 

 or to the plane of the face of the spikelets (fig. 5) instead of parallel 

 with it, as in the case of common wheat. 



The awns of durum wheat are much longer than those of any variety 

 of common wheat. They vary in length from 1 to 2 J decimeters or 

 more. The long, stiff awns and the compact head give the plant 

 much the appearance of barley, for which it is often mistaken by 

 those not familiar with the crop. 



The kernels of durum wheat are larger than those of common wheat 

 (fig. 6), varying from about 7 to 10 mm. in length, with an average 

 lengtn of 8 to 8 J mm. As the name indicates, the kernels are very 

 hard, the endosperm being entirely corneous. The seed coats are 

 unpigmented. The effect of the completely corneous endosperm and 

 unpigmented seed coats is a kernel of a clear amber appearance, 

 14644°— 18— Bull. 618 2 



