346 Bulletin 313 



Yield is thus dependent on several distinct characters that are doubtless 

 inherited separately. Indeed, many more factors than the above are 

 concerned in determining the yield. 



Another important type of variation is found in the direction of growth 

 of the culms. In some plants they grow strictly erect (Plate III, Figs. 4 

 and 6), while in other cases they bend strongly outward from the base 

 (Plate III, Fig. 3). All degrees of variation between these two types 

 can be found in different individuals. In some cases the culms bend at 

 the nodes, becoming markedly angular and producing an irregiilar, 

 scraggly plant. This is so marked a character in some plants that practi- 

 cally every culm bends outward and finally lies prostrate on the 

 ground, not by the breaking of the stem, but by the gradual bending 

 outward. This forms the so-called " lodging plants," which are in some 

 cases very marked types (Plate III, Fig. i). 



Culms and nodes. — The culms or stems of different plants vary in 

 height and number as indicated above, but they also vary in diameter: 

 some being thick and large, thus forming coarse hay, and others being 

 slender, forming fine hay. The range in variation is natvirally very great 

 on the same plant, but on some fine-stemmed plants the average diameter 

 of the culms is less than two millimeters, while on other plants the average 

 diameter is over three millimeters. The diameter of stem does not seem 

 necessarily to be correlated with height, as many tall plants have com- 

 paratively small stems. 



A difference of opinion exists among growers and dealers in hay as to 

 the size of stems desired in a good type of hay. Hay dealers because of 

 the market demands, usually prefer a rather coarse-stemmed hay, while 

 most farmers with whom the writer has consulted are inclined to prefer 

 fine stems. The true comparative value of coarse-stemmed and fine- 

 stemmed types can be determined only by nutrition and digestion anal- 

 yses and experiments, but it would seem reasonable to suppose that 

 coarse stems of the same height would be likely to contain less woody 

 fiber, comparatively, than would an equal weight of fine stems. The fine 

 stems, in order to be sufficiently strong and rigid to remain erect, would 

 probably require more woody tissue. 



The number of nodes is commonly five and this number very strongly 

 predominates ; but even on plants having mainly five nodes, usually a few 

 culms will have three or four nodes and others six nodes. Occasionally 

 a plant is found on which four nodes predominate, and more rarely one 

 that has six to eight nodes per culm. 



Considerable variation is also found in the length of the different inter- 

 nodes. Usually the lower internodes are short, the middle ones 

 longer, and the uppermost very long; but here, as in other characters, 



