OBSERVATIONS ON HARDINESS. 143 



many a lover of hard-wooded plants. The results upon shrubs 

 at the Garden have been already referred to. 



The alternate thawing and freezing of this vicinity must 

 also play an important part in the hardiness of plants here. 

 Alpine plants, or those from regions of perpetual cold during 

 the winter, do not" therefore adapt themselves readily, nor do 

 they take kindly to the succeeding fierceness of our summer sun, 

 after a winter of subjection to thawing and freezing. 



There is hardly sufficient data as yet on which to base a 

 statement as to what plants are hardy in the vicinity of New 

 York. Not until many investigators have recorded the results 

 of numerous experiments in various localities, and not until we 

 know more about the individual environment of a given species, 

 can we with any certainty explain the apparent contradictions 

 which seem to exist in the matter of plant hardiness. In so 

 far as the shrubs and conifers are concerned, it may be said 

 that, as a general rule, species from the Alleghenies and from 

 the regions somewhat to the north of New York are hardy here, 

 the belt of hardiness extending across the northern border of the 

 United States to the Rockies, and extending southward down 

 them at elevations of medium height ; while plants from the Pa- 

 cific coast, even as far north as Washington and Oregon, lead 

 a very precarious existence in this latitude. In Asia, hardy spe- 

 cies come from northern and middle Japan, northern China, 

 ]\Ianchuria and Siberia, with a few from the Himalayan region. 

 In Europe, of course many of the plants from the northern and 

 middle portions adapt themselves to conditions here, and from 

 the high mountainous regions of the southern portions come 

 some of our best conifers, while bvit few plants from the region 

 of the Mediterranean survive long. 



