382 ON THE SILVER ALDER 



The common alder, indeed, is on certain soils an excellent 

 nurse-plant and tree of shelter for narrow plantations on the 

 plain. It grows very quickly in youth ; it does not become 

 too high, maintains a good clothing of lower branches, and is 

 not liable to be thrown out of its balance. On the contrary, it 

 stands well up to the wind ; and I do not attribute any weight 

 to the supposition that its roots tend to retain moisture and 

 create swampy ground. Long experience and extensive obser- 

 vation as an arboriculturist, assure me that this apprehension is 

 chimerical, unless we plant the alder close to a spring, and allow 

 it to obstruct the outlet, when a birch would have much the 

 same effect. 



In narrow plantations a contrary evil is that which constantly 

 supervenes. After a very few years the soil becomes so dry and 

 so much exhausted from the wind sweeping through it, and car- 

 rying away all the fallen leaves which ought to lie and rot upon 

 the ground annually, that every kind of tree suffers from want 

 of humidity. 



If the alder could retain humidity in such plantations, upon 

 any soil, it would be invaluable, but it is incapable of doing so. 

 And the objection to the common alder as a tree of shelter in 

 small exposed plantations, and in the somewhat dry climate of 

 the cultivated country, is, that it is short-lived, and dies out 

 suddenly when twenty or thirty years old, leaving no young- 

 offspring to succeed it. It cannot bear our scourging winds in 

 Northern Britain, unless favoured by moist soil to supply the 

 loss by evaporation, though, curiously enough, it thrives well 

 under the hot sun of Kent, Surrey, and Hampshire, even on 

 poor dry parts of the Weald, and affords excellent coppice; but 

 then, vegetation there of every kind is greatly more vigorous 

 than with us. The earth is warmed to a much greater depth by 

 the sun's rays; and semi-aquatic plants, like the alder, can com- 

 pensate to themselves for the greater heat by sending down their 

 roots into a lower stratum. 



But if the common British Alder, alnm glutinosa, cannot be 

 depended on as a long-lived and reproductive plant, in planta- 

 tions, for shelter upon inferior soils on our north-eastern side ot 

 the Island, there is another alder which will be found to com- 

 pensate for the shortcomings of our native species, and this will 

 be a really valuable acquisition to any planter who will take the 

 trouble to propagate it ; for, happily, he may soon make himself 

 independent of the uncertain supply of this excellent nurse-plant 

 in the nurseries. The Silver Aider, otherwise called the hoaiy 

 and the Elm-leafed Alder, almis incana, grows even quicker 

 than the common species upon damp or on stubborn clay soils ; 

 and not only so, but in five or six years it begins to throw up a 

 number of offsets or suckers, from which any number of young 



