mannet every species, variety and hybrid possesses a scope of 

 sensitiveness of root and top to conditions of temperature, con- 

 sidered either separately or conjunctively, which is different from 

 that of any other species, variety or hybrid. 



HABIT OF GROWTH. 



The peculiar sensitiveness of the grape vine to temperature 

 -conditions would not deserve the amount of consideration, that 

 it does, if it did not exert its influence in other directions, which 

 makes it of the greatest consequence in regard to size, vigor, 

 hardiness and other qualities oft the grape vine. Its most im- 

 portant influence it probably has on the growth habit of a vine, 

 which seems to be principally governed by it. A vine which is 

 affected by a certain degree of coldness more than another one; 

 provided other things, as form of root system^ size of roots and 

 nature of soil, are the same, can not start growth during spring as 

 soon as the latter, but nlay become hardier in enduring drouth 

 and heat or less hardy, if its growth habit-incapacitates it in taking 

 full advantage of the most favorable moisture conditions of the 

 soil. It may become hardier in countries with long and dry 

 summers for the reason that its vital energy i? not so quickly 

 exhausted. A vine always suffers most from adverse conditions. 

 if these affect it after it has ceased its seasonal activity. 



In regard to the growth habit of different vines, I have 

 divided the native American 'species into two classes, free and 

 sluggish growers. The difference between the two is in their 

 different scope of sensitiveness to temperature conditions of soil 

 and atmosphere and much more in that of their roots than of 

 their tops, or in other words, while there is little difference between 

 the tops of free and sluggish growers in this respect, the latter 

 have a root which is mare easily affected and retarded by a low 

 temperature than their tops. But possibly it is the other way. 

 Sluggish growers may have about the same degree of sensitiveness 

 in root and top. On account of the soil being colder where the 

 roots are than right near the surface eithqr below or above, the 

 roots can not be as active as the tops. Free growers possibly 

 have a root which is much less affected by the same low tempera- 

 ture than their tops. But the result would be the same. At 

 least the root of sluggish growers is much more easily retarded by 

 certain temperature conditions in the soil, than their top is by 

 those in the atmosphere, as both generally occur at the same time. 



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