32 



THE CEREALS IN AMERICA 



shaped. They vary considerably with variety and thereby fur 

 nish means of distinguishing varieties. They may vary in coloi 

 from hght yellow to black, uniformly or in streaks, may be 

 smooth or hairy (sometimes called velvety), may vary in shape 

 and length. The keel varies in width and distinctness and its 

 tip or beak in length and sharpness. The 

 shoulder, which is that portion of the glume on 

 either side of the keel, and its tip (auricle) vary 

 in width and shape and the notch between the 

 auricle and the keel varies in depth or may be 

 wanting. The apical glumes, i. e., the outer 

 glumes of the apical spikelet, vary from the othei" 

 outer glumes and should be separately described. 



59. The Spike. — These spikelets in the grass 

 family are arranged in two ways, viz., on a more 

 or less lengthened branch or rachilla, as in the 

 oat, when the whole head is called a panicle; 

 or joined directly to the stem (i. e., by a very- 

 short rachilla), as in wheat, rye and barley, 

 when the head is called a spike. (51) In wheat, 

 rye and barley, as in several other species of 

 the grass family, the spikelets are arranged alternately at the 

 joints of the zigzag jointed stem or rachis, the stem being 

 excavated on the side next the spikelet. In the wheat genus 

 {Tritictim L.) there is but one spikelet at each joint and 

 it is placed, flatwise, usually on a single spike. There is 

 usually borne on the rachis at the base of each spikelet a growth 

 of short bristly hairs, to which Scofield has given the name of 

 basal hairs.^ These may be either white or brown in color 

 and may vary in length or be wanting. Often in the cultivated 

 varieties and always in the wild species, the lower one to four 

 spikelets are sterile. The empty glumes are somewhat broader 

 than the flowering glumes. The number of spikelets in a spike 



Front and side 

 view of spike- 

 let, showing 

 mode of at- 

 lachnnent to 

 rachis. 



IT. S. Dept. of Agr., Bureau of Plant Ind. Bui. 47, p. 14. 



