. The cereals in America. Grain. 32 THE CEREALS IN AMERICA. shaped. They vary considerably with variety and thereby fur- nish means of distinguishing varieties. They may vary in color from light 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
. The cereals in America. Grain. 32 THE CEREALS IN AMERICA. shaped. They vary considerably with variety and thereby fur- nish means of distinguishing varieties. They may vary in color from light 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. Thd apical glumes, i. e., the outer glumes of the apical spikelet, vary from the other 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 {Tritiann 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- tachment to rachis. I U. S. Dept. of Agr., Bureau of Plant Ind. Bui. 47, p.
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