ACCLIMATION OF PLANTS. 



ACCLIMATION OF PLANTS. 



In modern botany, Acanthus is a genus of 

 herbaceous plants found in the South of ': 

 Europe. Asia Minor, and India, belonging to 

 the natural order Acanthnceae. 



ACCLIMATION OF PLANTS. This term 

 has been applied to the act of accustoming 

 plants to support a temperature or a climate 

 different from that in which they are found 

 originally growing. This differs from natu- 

 ralization, which is the act of transporting or 

 transferring a plant into a country different 

 from its native place of growth. Nobody can 

 deny the possibility of these naturalizations ; 

 but there are some doubts upon the acclima- 

 tions of plants, doubts which have been corro- 

 borated by M. Schubler (Linnxa, 1829, p. 16) ; 

 and it renders this important question the more 

 deserving of examination, that the facts which 

 are reported are complex and somewhat con- 

 tradictory. 



On the one hand, we see wild plants appear 

 fixed within the same climate from the epoch 

 of which we have any knowledge, and culti- 

 vated trees, such as the olive, that have for 

 many centuries kept within the same limit. 



On the other hand, we see certain trees, 

 such as the horse-chestnut, which, although 

 originally from the tropics, have reached as 

 far north as Sweden. We see that in garden- 

 ing, the Aucubajapunica and the Paeonia Mont an, 

 after having been cultivated in the hothouse, 

 have passed into the greenhouse, and now flou- 

 rish in the open air. But before we infer from 

 these facts the possibility of acclimation, it 

 will be necessary to analyze them more fully. 



Taking the instance of a plant which may 

 have been placed at the first in the hothouse, 

 and afterwards cultivated in the open ground, 

 what are we to conclude, but that, while igno- 

 rant of its nature, and while its rarity rendered 

 it more precious, we were unwilling to run the 

 risk of losing it There is not a gardener, or 

 one who has had the management of a botanic 

 garden, who has not made such calculation a 

 hundred times, and who, doubtful of success, 

 has been led to follow this prudent course with 

 a multitude of plants. Those plants which are 

 received from tropical countries are usually 

 thus treated, on the supposition that they par- 

 take of the general nature of plants brought 

 from those countries ; and we afterwards try, 

 by groping in the dark, those which form ex- 

 ceptions to the general law. We thus succeed 

 in naturalizing some of them ; but this does not 

 yet prove that they have been acclimated, for 

 they have not been exposed on their arrival in 

 the climate they were afterwards seen to sup- 

 port. Even had this been done, the experiment 

 would have been frequently doubtful ; for when 

 plants arrive in Europe they are for the most 

 part weak, and too young to try the experiment 

 with ; while every one knows that young 

 plants, such as those of the bead tree and the 

 silk tree, will thrive in a temperate climate in 

 their adult age, if they are very vigorous when 

 planted, but which are easily destroyed by the 

 frost when young. 



An exact knowledge of the manner of living 

 of each species tends to explain some of the 

 illusions which we are apt to fall into on this 

 subject Thus, when a plant newly arrived in 



Europe, and consequently little known, is cul- 

 tivated in the open ground, it often happens 

 that it is placed in a soil or a position contrary 

 to its nature, that it is watered too much or too 

 little, and that it is pruned unseasonably, and 

 the like ; it consequently perishes without the 

 temperature of the climate being to blame. 

 Some years afterwards its nature becomes 

 better known, and the management which it re- 

 quires ; it is planted anew in the open ground, 

 is properly cultivated, and it succeeds, and we 

 then say it is acclimated, while it is simply 

 naturalized. 



The greater number of cultivators think 

 that plants produced from seeds collected in 

 the same country are much stronger than those 

 produced from foreign seeds, and make this an 

 argument to prove the doctrine of acclima- 

 tion. Sir Joseph Banks (Trans. Hort. Sue. i. 

 21), in particular, adduces in favour of this 

 opinion the culture of Zlzania aquatica, esta- 

 blished by him at Spring Grove ; but he also 

 relates that the first seeds collected in England 

 produced delicate plants, and the second strong 

 plants, so that this example proves as much 

 against as in favour of the theory. Dr. Mac- 

 culloch, also (Jour/i. of Science, 1825, p. 20 ; 

 Ferwts. Bull., Sc. Agr., ix. p. 262), in his Essay 

 on the Island of Guernsey, strongly doubts this 

 pretended superiority of plants coming from 

 seeds. We will not stop to notice that this 

 opinion is in opposition to the very generally 

 received idea, that the changing of seeds is 

 useful. We do not think it less probable that 

 those seeds taken from trees supposed to be 

 languishing, in consequence of not being yet 

 properly acclimated, produce young plants 

 much stronger than those which are taken 

 from trees more healthy, and growing in their 

 natal soil. We will not discuss that which 

 certain cultivators, such as M. J. Street (Trans. 

 Hort. Soc., viii. 1 ; Ferussac, Bull., Agr.), assert, 

 that the individual plants coming from cuttings 

 are much stronger than those coming from 

 seeds ; but we will ask whether this experi- 

 ment has been made with any degree of cer- 

 tainty, that is to say, in a comparative manner ; 

 and when the fact is so, that native seeds have 

 had better success, whether this may not have 

 arisen from the circumstance that certain sorts 

 of seeds do not succeed well when they are not 

 sown immediately after maturity, as in the case 

 of the coffee plant, or perhaps from their being 

 a greater number of seeds to dispose of, and 

 more of them sown 1 In fine, supposing that 

 experiments are in accordance with the ad- 

 mitted opinion, does this prove any thing more 

 than that a tree which produces good seed is 

 of a nature to accommodate itself to the soil; 

 and is not this rather a proof of naturalization 

 than of acclimation ? Let us see if there 

 exist any clearer proofs of the reality of accli- 

 mation. 



One of the principal results of culture is the 

 formation of varieties which otherwise would 

 have no existence in nature, and which have 

 different degrees of susceptibility according to 

 the temperature. We know that these varie- 

 ties, in many instances, are much more delicate 

 than the wild species. We may instance the 

 varieties of double flowers, which are less 



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