PROPAGATION BY GRAFTING, ETC. 245 



grafted on the laburnum, as do the different varieties of Pyrus Aronia 

 when grafted on the common thorn ; the common lilac attains a large 

 size when grafted on the ash ; and Tecoma radicans, when grafted on 

 the Catalpa, forms a round head with pendent branches, which are 

 almost without tendrils. The hardiness of some species is also in- 

 creased by grafting them, as in the case of the Eriobotrya japonica 

 on the common thorn, and the Pistacia vera on the P. Terebinthus ; 

 the Quercus virens is rendered hardier by being grafted on the ever- 

 green oak ; but in other cases, the species are rendered more tender, 

 as when the lilac is grafted on the phillyrea. Those species that are 

 rendered hardier by grafting have probably tender roots, and by being 

 placed on such as are hardier, they suffer only from the cold at top, 

 instead of being injured by the effects of cold both at root and top ; or 

 if they grow more stunted, they will also be less susceptible of cold. 

 The period of flowering is well known to be accelerated by grafting ; 

 and hence, both in the case of fruit-trees and ornamental trees and 

 shrubs, the shoots of seedlings are frequently grafted on the extremi- 

 ties of the branches of old trees ; in consequence of which they blossom 

 several years sooner than if left on their own roots. The mountain- 

 ash, and the different varieties of Pyrus Aria, produce double the 

 number of fruits when grafted, to what they do on their own roots. 

 The increase of the size of fruits, more especially of kernel fruits, is 

 said by Thouin to be often from a fifth to a fourth part, but the 

 number and size of seeds produced is diminished. The flavour as well 

 as the size of fruit is said to be altered by the graft. Thus pears are 

 said to become gritty on quince or thorn stocks ; and the greengage 

 plum to vary in flavour, according to the kind of plum-stock on which 

 it is grafted; producing insipid fruit on some stocks, and fruit of the 

 most delicious flavour on others ; the cherry also, when grafted on the 

 Cerasus Mahaleb, on the wild cherry, on the bird cherry, or on the 

 common laurel, will produce fruit very different in flavour on each. 

 The fertility or sterility of fruit-bearing trees is likewise greatly 

 affected by grafting. The duration of trees is greatly altered in 

 certain cases by the graft ; the apple on the paradise stock is generally 

 shorter lived than on the crab-stock ; while the Pavia, grafted on the 

 horse-chestnut, has its longevity increased. The period of leafing and 

 flowering is also occasionally changed by the graft, the general effect 

 of which is to produce a somewhat earlier vegetation ; because the 

 graft, by arresting the descent of the sap, produces in some measure 

 the effect of ringing. So much for the influence of the stock upon the 

 scion. 



The influence of the scion on the stock is very limited, and as far 

 as experience has hitherto gone, it consists only in communicating a 

 change of colour ; buds of the variegated common jasmine having 

 been inserted in a species without variegated leaves, and having 

 communicated its variegation to the entire plant, both above 

 and below the graft. The common alstonia has likewise become 

 variegated by A. Thompsoni being grafted upon it. Similar facts 



