| Summary: | 154 is at present bred to fit cool growth conditions within moderate extremes as to heat and drought. Roughly, as far as the growth of the seed crop is concerned, its culture may be placed as co-existent with successful spring wheat regions, while the fibre crop is produced in regions of heavier rainfall and somewhat cooler and more cloudy skies than spring wheat is usually successfully grown. The crop may also be said to possess either general capabilities or varieties and strains, which allow of the production of fair crops of seed flax at least to the southern limits of winter wheat producing regions. Whether grown for seed or fibre purposes, the flax crop of the northern hemisphere is quite generally found between the limits of the July isotherms of sixty and eighty degrees Fahrenheit. Roughly drawn, these lines run as follows : That of July 60 degrees passes approximately thro San Francisco northward along the coast range to the Arctic circle in Alaska, thence southward and eastward thro Winnipeg and north New England, thro north Ireland, Hull, Christinan, Archangel, Michaelovka, Verkhoynsk, Siberia and north Saghalien. That of July 80 degrees passes approximately through Gulf of California; Pierre, South Dakota, Des Moines, Charleston, South Carolina, Gibraltar, Tripoli, Constantinople, Bokhara, Pekin and Nagisaki. A rough study of isothermal lines, as now mapped, indicates that the various flax areas of the world fall quite naturally in temperature belts of great similarity according to the type of flax that is grown,' thus the seed flax areas for the production of oil are found under temperature conditions very similar as to the mean temperatures of the growing months. It is also found that the even climatic conditions of Brussels, St. Petersburg, and the North Pacific Coast of Oregon and Washington, North Michigan, and Wisconsin, furnish about equal qualities of the better types of fibre flax. The only point of variation seems to be that the seed producing areas of our northwestern plains reach a higher July and August mean temperature than most of the flaxseed producing areas of Europe and Asia attain. It is necessary, however, in contrasting isotherms to consider not those of a single month alone, but those of the properly contrasting growth periods, as for example, the periods of blossoming and boll formation. These periods of growth, it will be found, do not strike the same calendar months in the different flax districts of the world, but, when 27 x 21 cm. Fargo : North Dakota Agricultural College, Government Agricultural Experiment Station for North Dakota, 1906. Bulletin no. 71. p. [139]-215.
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