THE EAR OR HEAD 23 



arising from the crown, and if these be carefully removed a small bud 

 will be found at the base of each leaf. These buds develop into 

 branches or " tillers." The number that develop, however, depends 

 on conditions. If the soil is poor or cold, so growth is not vigorous 

 at first, perhaps no tillers will develop, while very favorable condi- 

 tions will stimulate the buds to growth. Hence we find that on cold, 

 clay soils plants seldom tiller so freely as on warm, sandy soils. 

 Crowding the plants by thick planting also suppresses the tillers, 

 while thin planting favors them. Wheat plants placed wide apart, 

 6 to 8 inches each way, on rich soil will produce 10 to 20 stems from 

 a seed, but under ordinary field planting not more than 2 or 3. The 

 following data, from the Nebraska Experiment Station, 1 shows the 

 effect on tillering of oats with different rates of planting : 



Tillering of Oats 



Pecks of seed Stems per Total number of 



sown per acre 100 plants stems per acre 



4 466 1,419,000 



8 279 1,732,000 



16 140 2,283,000 



The Stems of Cereals. The stem of corn is filled with pith, but 

 in wheat, oats, rye, and barley the stem is usually hollow, with solid 

 joints or ziodes. However, in a few wheats, as the spelts, the stem 

 is partly or entirely filled with pith. The number of joints in corn 

 varies from about 8, with short early varieties, to 12 to 14, with tall 

 late varieties. In the small cereals 4 or 5 nodes is the usual number. 



One leaf arises from each node, the largest leaves coming from 

 about the middle of the plant. In wheat there are usually about 

 three leaves on the stem, and in oats about four. 



The Ear or Head. In all the small grains (wheat, oats, barley, 

 rye) the ear is borne at the top, but in corn only the tassel or male 

 flower is borne at the top, while the ear is borne on the side. Both the 

 male and the female flowers are borne in one head (called perfect 

 flowers) in the small cereals, but in corn are separated in the tassel 

 and ear. Since all cereals are grasses, the structure of the head and 

 flower is similar in the main features, but varies in details. To un- 

 derstand the structure fully a careful comparative study of details 



1 Nebraska Bulletin 127, p. 18. 



