"The qualities that give value to durum wheat are its ability to withstand drought and its resist ance to rust. It is being grown now in regions of light rainfall, under which conditions it produces larger yields than any other spring variety of wheat. It has not so far proved more productive than winter wheat, and consequently has not taken a place among the crops of the winter wheat region.
"Some varieties of durum wheat have proved sufficiently hardy to live through the win ter in southern Kansas, and by selection of hardy individuals its production will doubtless be extended northward. It has been grown as a winter wheat in an experimental way at the Nebraska Experiment Station for three years. If it can be developed into a successful winter wheat it will doubtless replace the com mon varieties in much of the great plains re gion ." (T. L.
Lyon.) (8) Polish wheat (T. Polonicum). Fig. 901.—The Polish wheat is characterized by having the palea of the lowest flower half as long as the flowering Blume, while the outer glumes equal or exceed in length the flowering glumes. This wheat may have some value for arid climates, but is not productive.
The plant is sometimes called Giant or Jerusalem rye, because of the resemblance of the seeds of the two. It can be used for the making of macaroni. It is grown in southern Europe.
Geographical classification.— The United States Department of Agriculture, in 1895, made a collection of more than one thousand supposedly distinct varieties, but after testing these for several years it was found that very many were identical and that only one fourth of the number were of any value to the American growers. It will be readily un derstood that a single variety grown under the wide range of climate and varying condi tions which are to be found in this country would in the course of a few generations show widely differing charac teristics. Few cultivated plants are so susceptible to such in fluences.
In his"Basis for the Improve ment of American Wheats," Carleton divided the entire country into districts accord ing to the general character of the grains produced in each.
A study of these districts reveals the fact that the va rieties usually grown in any one given section will all pos sess so nearly the same values as to warrant their classifica tion together and thus give the product of each district a dis tinctive character. According to the grouping we will have : (1) The soft wheat district, including mainly the New Eng land and middle states.
(2) Semi-hard winter wheat district, including the north central states.
(3) The southern district, in cluding the northern part of the southern states.
(4) The hard spring wheat district, including the upper Mississippi river basin.
(5) The hard winter wheat district, including parts of the middle states of the plains.
(61 The durum wheat region, including parts of the southern states of the plains.
(7) The irrigated wheat district, scattered over the Rocky mountain region.
(5) The white wheat district, including the larger part of the Pacific coast states.
This classification recognizes certain qualifica tions, chief among which are color of grain and percentage of gluten, which form the basis of the Since these qualifications are largely affected by the particular section of the country where the types are produced, it is a fair inference to speak of such a classifica tion as a geographical one.
From such a study as the above it can readily be seen that there is no single variety or even type that can be sug gested as the best for the whole country, and even if a single variety were universally adopted it would be but a few years until it would be found as varying in character as the many sections where grown. So marked is this that markets have been created, and with the opening up of new areas, producing grain of unusual character, the milling industry has at times undergone a com plete change.
The production of varieties.
The greater number of the common varieties of wheat are the result of chance rather than of any scientific effort for improvement. Wheat is a self-pollinating plant, and be cause of this, rarely fails to reproduce true to its charac teristics. As every grower knows, however, there will occasionally appear a new or even unusual form in a field of grain which may or may not resemble the variety among which it may be growing. Such forms are known as "sports," and are the result of accidental crosses between plants of the same or different varieties. It is probable that these occur more fre quently than they are discovered and that close observation would reveal many new and superior varieties that are never isolated and reproduced as distinct varieties. Without doubt the great major ity of our commonly known wheats have thus originated, and it is only within a comparatively recent period that what are known as "pedigree" or scientifically produced varieties have been placed in the hands of growers. Every wheat growing region of the world has been explored for the best varieties it was able to produce, and it is safe to say that few promising varieties which can be found anywhere remain to be tested. Vast improvement to the wheat crop has thus resulted, particularly through the introduction many years ago of what are known as Mediterranean varieties. With the reaching of the limit of possible improve ment by this means, attention is being more directed to the artificial production of new varie ties and the future improvement of wheat, for par ticular purposes as well as increased yield, will be secured by these means.