136 FIELD CROPS 



171. Season of Growth. Wheat is grown successfully on 

 some of the higher altitudes at the equator, and from there 

 all the way to within 200 miles of the Arctic Circle. Wheat 

 does best in a temperate climate where the rainfall is not 

 less than 20 inches, largely distributed through the growing 

 season, and where the seasons are sufficiently long to allow 

 100 to 125 days of good growing weather free from frost. 

 Spring wheat will mature in from 100 to 125 days from the 

 time of planting. Winter wheat requires about 100 days to 

 mature from the beginning of the growing weather in the 

 spring. 



172. Botanical Characters. The wheat plant is a true 

 annual, though in some instances it has been changed into 

 what is known as a winter annual, being sown in the fall and 

 maturing early the following summer. The numerous 

 fibrous roots grow in whorls from the lower joints of the stem. 

 Most of the roots of the wheat plant are usually found in the 

 surface soil, though under favorable conditions they have 

 been known to grow to a depth of 7 feet. However, such 

 growth is unusual. 



Like most of the grasses, the stems of wheat are jointed 

 and hollow, except in the variety known as emmer, in which 

 the stems are more or less pithy. During the early stages of 

 growth, the stems are very short, though they very early 

 develop the entire number of nodes and internodes. For 

 several weeks the plants devote their energies to producing 

 roots and leaves and in developing new stems, or stools. 

 When a good growth of leaves and roots has been developed, 

 the stems shoot up quickly, simply by lengthening the inter- 

 nodes. Stooling is accomplished by buds at the lower nodes 

 developing into culms. In this way a large number of stems 

 may be produced from one seed, the number being deter- 

 mined by the soil and climatic conditions and the thickness, 



