24 PRESENT-DAY GARDENING 



clarense, raised at Highclere in 1826, where R. arboreum, 

 which had been introduced from India six years earlier, 

 was crossed with R. catawbiense. Although the last named 

 had been crossed with the common R. ponticum, the Indian 

 blood was needed to give variety of colour and those other 

 qualities which characterise their hybrid descendants. 



Among the earliest breeders of Rhododendrons was 

 Dean Herbert. In his classical treatise on Crosses and 

 Hybrid Intermixtures among Plants, written nearly a cen- 

 tury ago, he pointed out that Rhododendrons offered a rich 

 field to the hybridisers. He believed that all the species 

 would intermix, and had even tried to cross R. indicum with 

 other species, but found it refused to blend with any but its 

 own immediate kindred, which is the experience of breeders 

 to-day. The Dean crossed the Pontic Azalea with Rhodo- 

 dendron, and the American Azaleas with R. arboreum. He 

 noted that the hybrids from R. arboreum were impatient of 

 wet ; also that they never bore fertile seeds. He also raised 

 crosses between the Pontic and American Azaleas, between 

 R. sinense and R. calendulaceum (thus anticipating the suc- 

 cesses of Messrs. Cuthbert and Koster), between R. ponticum 

 and R. catawbiense (" an amazingly florid hybrid "), between 

 R. maximum and R. arboreum (surely a good cross, but 

 not now known to be in existence), between R. caucasicum 

 and R. arboreum, and others. He recognised the import- 

 ance of breeding for a later flowering habit and urged 

 the use of R. maximum, which flowers in midsummer, to 

 counteract the bad influence in this respect of R. arboreum. 



Breeders to-day might make more use of the North 

 American R. maximum. It grows on the Appalachian 

 mountains up to an elevation of 3000 feet, often forming 

 thickets hundreds of acres in extent, and is a bushy tree up 



