Page:Popular Science Monthly Volume 18.djvu/819

Rh. 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 hardiness 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 greenhouses, 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 Thuiopsis borealis and Thuja gigantea, natives of northern Oregon, fail even under the best treatment sometimes, during winters of New York and Philadelphia. Some explanation may of course be attempted by adducing the peculiar climate of the Pacific coast in its rainy seasons, but then consider 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, comparatively, 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. Rhododendrons, hollies, and all evergreen 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 altogether. On the other hand, what can we say to the evergreen Thuiopsis Standishii doing better here than in England, and Thuiopsls dolobrata better in England than in America? Japanese maples, that seem to grow more thriftily and vigorously here than in Japan, give evidence