THE RELATIVE HARDINESS OF PLANTS. 799 



ness. One of the salient instances of diversity in hardiness of nearly 

 related plants is the behavior of Japanese persimmons in this country. 

 It was confidently expected that they would prove hardy in America, 

 because native persimmons were hardy, and because the general hardi- 

 ness of Japanese plants in America had been often demonstrated. 



But fifteen years' trial of a few detached plants, and five years' 

 trial of thousands together of these Japanese persimmons, prove their 

 hardiness more uncertain than that of the American persimmon. 

 What shall we say of the other Japanese plants that fail to prove hardy 

 in America north of Tennessee, or even Florida of the Osmanthuses, 

 best described as resembling the hollies in appearance, of the privets, 

 live-oaks, Ancubas, etc. ? They are common enough plants in our green- 

 houses, but only in very sheltered positions, and during mild winters, 

 will any of them live uninjured in this climate. Such facts must be 

 very perplexing to any theorist who attempts to explain why and where 

 this or that plant is hardy. 



Or let us change somewhat our problem, and consider why plants 

 belonging to countries much nearer home than Japan, but in similar 

 latitude, fail to prove as hardy here as many Japanese plants. Note 

 the fact, moreover, that these trees I shall next refer to come from 

 even colder regions than Japan, and yet Japanese plants of the same 

 genera are usually more hardy. The ways of plants, verily, become 

 still more puzzling when we find such evergreens as Tliuiopsis horecdls 

 and Thuja gigantea, natives of northern Oregon, fail even under the 

 best treatment sometimes, during winters of New York and Philadel- 

 phia. Some explanation may of course be attempted by adducing the 

 peculiar climate of the Pacific coast in its rainy seasons, but then con- 

 sider that many of these plants are found eight and ten thousand feet 

 up in the mountains, and also that, when we pass a few hundred miles 

 farther east in the same parallel of latitude, we find the same varieties 

 and even species such as the Douglas fir becoming hardier. Few, com- 

 paratively, of the California native deciduous trees are hardy in the 

 East, and even for many Oregon trees of the same class, such as Acer 

 macrophyllum, there is much suffering in store during hard winters on 

 the Atlantic coast. Passing over to Northern Europe, the behavior of 

 trees is still more perplexing. To be sure, as a rule, the Gulf Stream 

 insures milder climate in the same degree of latitude, but away up in 

 northern Scotland, and even in Norway, we find many evergreens more 

 hardy than in the more temperate latitude of New England. Rhodo- 

 dendrons, hollies, -and all evei'green shrubs, if not all evergreen trees, 

 do better there, which is doubtless to be attributed in part to a moister 

 climate and more equable temperature, but it can hardly be that alto- 

 gether. On the other hand, what can we say to the evergreen Thxd- 

 opsis Standlshii doing better here than in England, and Thuiopsls dolo- 

 hrata better in England than in America ? Japanese maples, that seem 

 to grow more thriftily and vigorously here than in Japan, give evidence 



