48 BULLETIN" 1074, U. S. DEPARTMENT OF AGKICULTUBE. 
MILLING AND BREAD MAKING. 
Next to productivity, the value of wheat varieties for milling and 
bread making probably is of the greatest economic importance, as 
this is the principal use for wheat. There are significant differences 
in milling and bread-making values of different varieties. As in 
yield, these differences can be accurately determined only by careful 
experiments, identically conducted with comparable samples. Pre- 
vious authors have not used these differences in distinguishing varie- 
ties. Where definite experiments have shown certain varieties to be 
unusually good or poor for milling or bread making, these differences 
are here pointed out, following the description. 
RESISTANCE TO LOW TEMPERATURE. 
Hardiness or resistance to low temperatures consists of both the 
ability to survive low winter temperature and resistance to injury 
from spring and summer frosts. Very little is known concerning the 
latter character. The winter hardiness of several varieties was re- 
corded for three years by Eriksson (88) and the hardiness of many 
varieties was given by Koernicke and Werner {133). Following the 
descriptions here given, the writers have indicated a few varieties 
which are known to be especially winter hardy, but otherwise the 
character is not mentioned. 
RESISTANCE TO DISEASES. 
Wheat varieties are Imown which have more or less resistance to 
each of the various diseases of wheat. Practically all varieties of 
wheat have been grown in nurseries where they were infected either 
naturally or artificially, so as to be able to observe any marked re- 
sistance to stem rust {Pyaemia grammis), leaf rust (P. tritidna)^ 
stripe rust {P. glumarum) , and bunt or stinking smut {TiUetia tritici 
and T. foetens). The presence of resistance can be determined only 
when all varieties have been equally exposed to all strains of a dis- 
ease under conditions favorable for their development. A few varie- 
ties have shown a distinct resistance to stem rust or to bunt, and this 
fact is noted following their descriptions. 
CLASSIFICATION OF THE GENUS TRITICUM. 
Wheat belongs to the grass family, Poaceae (Graminese), and to 
the tribe called Hordese, in which the 1 to 8 flowered spikelets are 
sessile and alternate on opposite sides of the rachis, forming a true 
spike. Wheat is located in the subtribe Triticese and in the genus 
Triticum, where the solitary 2 to many flowered spikelets are placed 
sidewise against the curved channeled joints of the rachis. 
There are two sections of the genus Triticum, one including the 
old genus Aegilops, in which the glumes are flat or rounded on the 
