338 SYLVA AMERICANA. 



hereafter. The preparation of the soil, the mode of sowing, and 

 the different kinds of forest-tree seeds, have already been 

 described. All kinds of forest trees, however, are not raised 

 from seeds, either because they do not perfect a sufficient quantity 

 for the general purposes of propagation, or are accidental varieties 

 only of a species losing their characters of distinction when 

 reproduced from seed. The following modes of propagation are 

 found effectual when seeds cannot be obtained : first, by suckers, 

 second, by layers, third, by cuttings, and fourth, by grafting. 



1st. Suckers are shoots produced by the creeping roots of a 

 tree, which, when separated from the parent root and transplanted, 

 become perfect trees. They are generally sufficiently rooted in 

 the first season of their production, and they should not be 

 suffered to remain longer than two seasons attached to the root 

 of the tree ; for if continued longer, the support they derive from 

 the parent root prevents them from making independent roots of 

 their own in such abundance as they do when separated or taken 

 up at an earlier period. The spring is the most proper season 

 for taking them from the parent roots. When a sufficient numbeT 

 of rootlets appear on the sucker, no part of the root from whence 

 the sucker sprang should be left attached to it ; but where the 

 proper rootlets are deficient in number, a small portion of the 

 parent root may be left with advantage. The plants should be 

 planted in rows in fresh soil, and treated in all respects afterwards 

 as directed for seedling transplanted trees. The kinds of trees 

 chiefly reared in England in this mode are : 



Ailantlms glandulosa, . . Chinese Ailanthus. 



Populus alba, . . . Ahele Tree. 



Populus canescens, . . . Common White Poplar. 



Populus tremula, . . . Aspen. 



The first three kinds may also be propagated by layers. 



2d. Layers. The process of layering is well known : it 

 consists in bending a young branch (Plate 103) into the soil to a 

 certain depth, and elevating the top part of it out of the soil in 

 an upright direction ; in time the buried part takes root, and the 

 shoot becomes a perfect plant. The root which produces the 

 young shoots for layering is called the stool. Stools are planted 



