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W. C. Etheridge 
or oven obliterated, by a radical change in climatic environment. The 
conclusions of Jensen (1899) would seem to provide a basis for Berry's 
conclusion, for Jensen, on collecting varieties of oats from many countries, 
found that by far the heaviest grains came from countries having an | 
insular or a coast climate. 
In view of the many factors influencing them, the physical properties of 
grains are of no use in any classification beyond a mere arrangement 
of market grades. Classes based on such characters could not be expected 
to remain constant under the extremely wide range of climatic environ- 
ment in this country. And even under given conditions of environment, 
the variation in weight and in kernel content, according to the position of j 
the grain in the spikelet and in the panicle, would make difficult an accurate 
arrangement of types. 
THE PANICLE 
The panicle, or loose flowering head, exhibits among the wild forms 
of Avena no distinct taxonomic differences. Botanists mention the 
length and the form of the panicle as a general descriptive feature but 
not as a specific distinction. Among cultivated varieties, however, two 
characters of the panicles may be directly utilized in classification. These 
are its form, and certain peculiarities in the structure of its rhachis. 
Form of the panicle 
The form of the panicle is determined by the attitude of the branches. 
These may form the common, roughly equilateral panicle, as in A. sativa 
(fig. 24, page 136), or the unilateral panicle of A. sativa orientalis (fig. 13, 
page 111), or any variation of these types. In both the contrasting types 
the branches issue from various sides of the rhachis, but later assume 
different attitudes. The branches of the equilateral panicle spread out- 
ward from various sides of the rhachis and extend upward at an angle of 
about forty-five degrees, and, shortening toward the apex, form a rough 
pyramid. Panicles of this type may be compact and stiff, with each 
branch in an ascendant attitude along the line of its initial angle for its 
entire length; or they may be open and lax, with the branches ascend- 
ant but finally drooping from the middle outward. In unilateral panicles 
the branches incline from one side of the rhachis, and, extending upward 
