" HARDY" RHODODENDRONS 271 



there are hybrid offspring of R. maximum and R. 

 caiawbien.se such as R. wellesleyanum, which has 

 proved anything but hardy. Again, in the Arnold 

 Arboretum many plants of Delicatissimum, a hybrid 

 between these two American species and for the last 

 thirty years considered one of the hardiest and most 

 desirable of the Rhododendrons which have been 

 planted in New England, died from the effects of 

 the winter of 1914-15. Thus caution is necessary; 

 but, in cross-breeding among the five species of proven 

 hardiness, there is every possibility of evolving a very 

 tough hybrid race. But to ensure success it should 

 be done in this country as far north as possible, so 

 that the progeny may become inured to the climate 

 from their babyhood up. 



Except in time and place such work as is advocated 

 here is not altogether de novo. I do not know whether R. 

 brachycarpum has been experimented with; but the 

 others have, and with encouraging results, especially 

 /?. Smirnowii, a hybrid of which is giving much satis- 

 faction in the Arnold Arboretum. The Lace-wing 

 Fly is a bad pest on Rhododendrons in which the 

 undersurface of the leaf is smooth and green, but it 

 cannot attack R. Smirnowii the undersurface of 

 whose leaves is clothed with a felt of woolly hairs. 

 This species promises, therefore, to be of value in 



