482 Transactions of the London Horticultural Society. 



" From these places, and the other sources already named, a large number 

 of valuable returns of plants killed, and left alive, has been obtained ; and, in 

 order to insure all possible accuracy, they have been referred back to their 

 several authors, for such corrections and additions as it might appear desirable 

 to make. The result will I hope be found of great interest. 



" It is only by repeated observations of this kind that we can hope for 

 certain success in the important object of introducing exotic species hardy 

 enough to bear our climate ; consequently to multiply and systematize such 

 observations is one of the most useful employments in which the horticul- 

 turist can engage. It is far more likely to lead to results of importance than 

 attempts to acchmatize plants; an object which has already occupied so much 

 time to so little purpose, that I doubt whether any one case of actual acclima- 

 tization can be adduced ; that is to say, any one case of a species naturally 

 tender having been made hardy, or even hardier than it was originally. Not 

 to mention other cases in point, Cerasus Laurocerasus is as tender as it was 

 in Parkinson's time, and yet it has been raised from seeds through many gene- 

 rations ; the potatoe retains its original impatience of frost, and so does the 

 kidney bean, which last might at least have been expected to become hardier, 

 if reiterated raising from seed in cold climates could bring about that result. 

 The many beautiful and valuable half-hardy hybrids, lately provided for our 

 gardens, are no exception to this statement, for they are not instances of a 

 tender species being hardened, but of new and hardy creations obtained by 

 the art of man from parents, of which one is hardy and the other delicate. 

 Acclimatization, in the strict sense of the word, seems to be a chimsera. 



" What gives such evidence, as is now about to be adduced, its great 

 value, is the well known fact, that no botanist can ever tell with precision 

 whether a plant will support a climate to which it is unaccustomed. No one 

 has as yet succeeded in pointing out any decided connection between the 

 structure of plants and their powers of enduring cold, and consequently we 

 cannot judge a 2^riori what amount of cold a given plant will bear. If 

 this could be effected, one of the most important of all steps would have been 

 taken in the progress of horticulture, and we should be spared the loss and 

 disappointment which now attend all extensive attempts at naturalizing exotic 

 species. It is undoubtedly true, that particular natural orders of plants affect 

 particular and well marked climates ; as palms, the plains of the tropics ; 

 Cactaceas, the temperate and dry regions of America ; and epiphytal 

 Orchidacese, the hot and damp regions of all countries near the equator. 

 But even these cases are not free from striking exceptions ; we have the 

 fan palm {Chamwrops humilis) growing as far north as Rome, and the 

 wax palm {Ceroxylon andicola) flourishing on the mountain Quindiu, at 

 the height of nearly 9000 feet above the sea, in bleak places where the 

 temperature falls to 44°. Of Cactacese, a species of Opuntia, with no other 

 protection than a hand-glass, or occasionally in the most severe weather a 

 mat thrown over it, was able to sustain the late winter at Owston, near 

 Doncaster, where it must have endured a temperature of 9° Fahrenheit; 

 Opuntia ferox stood unprotected at Glasgow and Dropmore ; and according 

 to Nuttall, Melocactus viviparus and another are found in the elevated 

 mountainous regions of the Missouri, where they are exposed to " intense 

 frost." Finally, epiphytal OrchidaceEe have been found at the elevation of 

 14,000 feet on the Peruvian Andes, where the cold is very considerable, in the 

 case of Oncidium nubigenum ; Dendrobium denudans inhabits regions in the 

 north of India, where it grows upon oaks, and is occasionally exposed to 

 frost, according to Dr. Royle; and Mr. Hartweg met with a species of 

 Laelia (?) in the mountains of Leon in Mexico, on branches of oak trees, at 

 an elevation of 8000 feet above the sea, where it sometimes freezes. 



" Under these circumstances, speculation as to the laws which govern 

 such conflicting results, is in the present state of our knowledge premature, 

 and the only useful information which can be given consists of naked facts. 

 These facts are, however, of the utmost practical consequence, because they 



