308 PROPAGATION OF PLANTS. 



warm climates no such protection is required, and a cion set early in 

 the winter becomes fully united to the stock before a rapid flow of sap 

 begins in spring, and this no doubt is why Julius Atticus recommended 

 early grafting of the Grape in his time, or nearly two thousand years 

 ago. But early spring grafting is most generally practised in cold 

 climates, the cions being stored in a cool place where they will remain 

 dormant until wanted for use. The earlier they are inserted the more 

 likely they are to unite, and if not inserted early it is better to wait until 

 the leaves have unfolded on the stock and the sap has become somewhat 

 thickened through evaporation from the leaves. When vines are grafted 

 on roots below the surface, the cion, if not prevented, will throw out 

 roots of its own, and the benefit of a strong, old stock will be only tem- 

 porary ; but if these surface roots are removed once or twice a year the 

 old stock may continue to exercise its influence upon the cion for many 

 a year. Grafting by approach above ground is readily accomplished by 

 the usual mode during the early summer months, and this is probably 

 preferable to grafting below the surface where it is necessary to use 

 what are called "phylloxera resisting stocks," as some of our native 

 species of the vine are called in France and California. 



Weigela. See Diervilla. 



Wistaria. Very rapid- growing, woody, climbing plants, with pea- 

 shaped flowers in long, drooping clusters. One species ( W. frutescens), 

 native of the United States, and one ( W. Sinensis), in China. There are 

 several varieties of both species in cultivation, nearly all now common in 

 our gardens. Propagated by seeds, which are produced in great abun- 

 dance on old plants, by layers and grafting. Cuttings do not usually 

 strike root very readily when planted in the open ground, but will suc- 

 ceed if planted in sand under glass where they will receive moderate 

 heat. 



Zanthoxylnm (Prickly Ash). A small genus of ornamental and use- 

 ful shrubs ; the bark, leaves and fruit extremely pungent and aromatic. 

 The common native species found in our Northern woods is known as 

 "Toothache tree." Another species is found in the Southern States, 

 and several in the East and West Indies and other tropical countries, 

 besides in China and Japan. One species from the latter country (Z. pi- 

 perituni) is nearly hardy in my grounds, the terminal shoots only being 

 injured in winter. Propagated the most readily by cuttings of the roots. 



