88 THE SMALL GRAINS 



and the glumes many nerved. The common cultivated 

 oat, Avena saliva, Linn., which has awns of the persistent 

 lemmas straight, bent, or none, is thought to have 

 originated from the wild oat, A. fatua, Linn., which has 

 geniculate awns and deciduous lemmas, or from some 

 other similar wild species. 



78. Roots. In oats there are three seminal roots. 

 The crown from which the coronal or permanent roots 

 and main culms originate is about one inch below the 

 surface of the ground. The permanent roots are fibrous, 

 as in other cereals, and there is no tap root. The roots 

 of oats are larger and more numerous than those of wheat, 

 and therefore loosen and mellow the upper part of the 

 soil a little more. They attain a length of 110 cm. and 

 spread 94 cm., giving a root coefficient of 10340. The 

 roots of winter oats, or of any winter cereal, are usually 

 longer than those of spring varieties. 



79. Culms of oats are larger in diameter and more 

 succulent than those of wheat. As in wheat, at each 

 underground node of every culm, a bud may develop 

 which will produce another culm. The lower nodes of 

 this culm may in turn produce other culms, and so on. 

 The number of culms from one original kernel, or the 

 degree of tillering, varies greatly in different varieties 

 with the thickness of seeding and with other conditions. 

 Winter varieties tiller more than spring varieties, as in 

 other cereals. The culms are hollow. The height of 

 the plant varies from 2 to 5 feet. Love and Leigh ty 

 (1914, pp. 20-34) determined that " there are high, posi- 

 tive, and fairly stable correlations between average height 

 of plant and (a) total average yield, (b) total and aver- 

 age number of kernels produced, and (c) average num- 

 ber of spikelets per culm." 



