140 



AMERICAN VINES. 



north, and south-west of France, and was exclusively cul- 

 tivated in light siliceous soils. It was excluded, with good 

 reasons, from all calcareous soils; amongst the graft-bearers 

 which were most in use, it is the most affected by 



Fig. 72. Leaf of Vialla. 



calcareous soils. In siliceous and fairly fertile soil it has a 

 very great vigour, and is one of those giving the best results ; 

 occasionally its excessive vigour causes non-setting. Of al! 

 the American vines it roots most freely from cuttings, and the 

 bench grafts give with it the highest percentage of knittings. 



