HORTICULTURAL DIVISION 



675 



Region 12 is that part of the Rocky Mountains in- 

 cluded in Idaho, Montana, Wyoming, Washington and 

 Oregon. The temperature and rainfall vary greatly, 

 dependent on elevation and exposure. Many places are 

 suitable for a great variety of plants; others are suited 

 to only a few. 



Region /j includes the Rocky Mountains of Utah and 

 Colorado. It is similar to the region farther north, 

 except that the temperatures for the same elevation are 

 about seven degrees warmer. The plants that can be 

 used at an elevation of four thousand feet in Region 12 

 can be used at six thousand feet in this region. 



Region 14 includes the Rocky Mountains of Arizona 

 and New Mexico. It is similar to the region farther 

 north, except that temperatures for the same elevation 

 average about six degrees warmer than Region 13 and 

 thirteen degrees warmer than Region 12. Allowing four 

 degrees of temperature for each thousand feet of eleva- 

 tion would make possible the growing of a particular 

 plant in Region 14 at elevations fifteen hundred feet 

 higher than in Region 13 when the moisture conditions 

 are similar. 



Region 75 is the northern Great Plains area south to 

 Kansas and Colorado, extending from about the five 

 thousand-foot contour on the west to the black soils on 

 the east. It is extremely cold in winter in the north- 

 eastern portions, usually dropping to thirty or forty 

 degrees below zero Fahrenheit, while close to the 

 mountains it is twenty degrees warmer. The summers 

 are moderately warm. This region is generally recog- 

 nized as the northern part of the dry-farming area. 



Region 16 is the central portion of the Great Plains, 

 including the plains portion of Kansas, Oklahoma and 

 New Mexico; also portions of the plains in Colorado 

 and Texas. It extends eastward from about the five 

 thousand-foot contour on the west to the black soils 

 on the east. The rainfall varies from ten to twenty 

 inches. The climate is warmer and ha greater evapora- 

 tion than Region 15. It is the southern portion of the 

 dry-farming area. The plants succeeding in Region 15 

 will grow here, together with many others that do not 

 survive so much cold but have the same ability to 

 withstand hot, dry winds. 



Region 77 is the dry, hot portion of southwestern 

 Texas, with little rainfall. 



Region 18 is the subhumid black-soils country lying 

 just east of the dry-farming area of the northern Great 

 Plains and is intermediate as to moisture between 

 Region 15 and the more humid area to the east of it. 

 The winters are very cold and dry. The same types of 

 plants succeed here as in Region 15 with a little wider 

 range of varieties, as there is a little more moisture. 



Region 19 is the subhumid black-soils area of Kansas, 

 southern Nebraska, and most of Oklahoma. There is 

 more moisture than in the dry-farming country to the 

 west of it and less than in the area farther east. It is a 



locality of sudden variation in winter temperatures and 

 of hot winds in summer. 



Region 20 is the subhumid or transition region of 

 central Texas with black- and chocolate-colored soils. 

 In moisture conditions it is intermediate between the 

 dry-farming regions farther west and the humid climate 

 of eastern Texas. 



Region 21 is in the northern part of the prairie coun- 

 try, having a short growing season with frequent 

 droughts of more than thirty days and cold winters 

 with drying winds. The rainfall is twenty to thirty 

 inches, occurring mostly in the summer. 



Region 22 is that portion of the prairie country hav- 

 ing higher temperatures than Region 21, but subject 

 to similar cold drying winds in winter. The rainfall is 

 thirty to forty inches. 



Region 23 is the western part of the Great Lakes 

 forest area. The eastern portion is slightly warmer and 

 more humid than the western portion, the latter much 

 resembling Region 21. 



Region 24 is largely that part of the country influ- 

 enced by the Great Lakes, lying east of Lake Michigan, 

 extending south into Ohio and eastward to Lake On- 

 tario. There is considerable moisture in the atmosphere 

 in addition to a rainfall of thirty to forty inches rather 

 well distributed through the year. The winter temper- 

 atures are more moderate than in Region 23, and there 

 is usually a good snow covering giving protection to 

 herbaceous perennials. 



Region 25 includes the Ohio and lower Tennessee 

 River valleys and the Ozark Mountain region. The 

 winter temperatures are rather moderate with much 

 alternate freezing and thawing, while the summer is 

 warm with a thirty-day drought often occurring near 

 its close. The rainfall is forty to fifty inches. 



Region 26 includes the colder sections of the eastern 

 United States, comprising much of Maine, the moun- 

 tainous portions of New York, and a portion of northern 

 Michigan. It is characterized by cold winters with 

 heavy snowfalls and short summers of long days and 

 cool nights. The rainfall is abundant, and the heavy 

 snows afford excellent protection to herbaceous plants. 



Region 2j is the Appalachian Mountain country, in- 

 cluding much of New England and New York, most of 

 Pennsylvania, and the mountainous portions of the 

 States southward. The rainfall is abundant, usually 

 thirty-five to fifty inches, and is well distributed 

 through the season. In the colder parts the snowfall is 

 sufficient to give abundant protection to herbaceous 

 plants. 



Region 28 lies just east of Region 27 and includes the 

 Piedmont and some adjoining sections with similar 

 growing conditions. It extends from northern Alabama 

 northeastward across the Carolinas and Virginia to New 

 Jersey and the coast of Alassachusetts. It is warmer 

 than Region 27, with abundant rainfall except in late 



