. Field crop production; a text-book for elementary courses in schools and brief courses in colleges. Agriculture. 104 FIELD CROP PRODUCTION wheat and rye are hairy, while in barley and oats they are smooth. The lower leaves wither and die as the plant approaches maturity, and at the beginning of ripening only the upper leaf and the topmost internode are green. 87. The spikelets. â A spikelet is composed of two outer glumes, inclosing from two to five flowers, each with a flowering glume and palea. In the wheat plant only one spikelet grows from each joint of the rachis. The rachis may be de-
. Field crop production; a text-book for elementary courses in schools and brief courses in colleges. Agriculture. 104 FIELD CROP PRODUCTION wheat and rye are hairy, while in barley and oats they are smooth. The lower leaves wither and die as the plant approaches maturity, and at the beginning of ripening only the upper leaf and the topmost internode are green. 87. The spikelets. â A spikelet is composed of two outer glumes, inclosing from two to five flowers, each with a flowering glume and palea. In the wheat plant only one spikelet grows from each joint of the rachis. The rachis may be de- fined as that part of the stem which passes up through the head. The joints of the rachis are close together, thus forming a compact head or spike. The number of spikelets per head varies with different varieties, the thickness of planting, the condition of the soil, and â with the weather. The number varies from 10 to as many as 50 or more. In fertile soils more spike- lets are produced per head than in poor soils. A thin rate of seeding also favors the production of a larger number of spikelets. Some varieties naturally have a larger number of spikelets per head than do other varieties. At the base of the head there are usually one or more sterile spikelets, â that is, spikelets in which the flowers do not become fertilized and produce kernels. This varies with the growing season and with the rate of planting. Un- favorable grov/ing seasons and a thick rate of seeding are favorable for a large number of sterile spikelets. The spike or head may vary in length and in shape. The. Fig. .33. âVariation in size of head and number of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Livingston, George. New York, The Macmillan company
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