20 PRESENT-DAY GARDENING 



resisting nature of their hybrids is sure to be more or less 

 influenced by them. The quality of the soil that is suit- 

 able for garden Rhododendrons need not be what is known 

 as rich, as they certainly grow well and are happy when 

 planted in a light, sandy soil over a gravel subsoil. 



The Swamp Honeysuckles are chiefly natives of north- 

 eastern regions and high mountain ranges. The earliest to 

 flower are R. canadensis (Rhodora) and R. nudiflorum in 

 April, then R. calendulaceum and R. occidental in May and 

 June, the latest being R. arborescens and R. viscosum, which 

 are in bloom in July. They are abundant in swampy land, 

 often at considerable altitudes, and when in flower they 

 produce an effect of great magnificence. 



EUROPE 



It is remarkable that, although the climate and other 

 conditions in many parts of Europe are specially favourable 

 to Rhododendrons, only very few species are natives, and 

 these chiefly in alpine regions. There are evidences in the 

 Miocene rocks of Central Europe of Rhododendrons, and 

 they were quite common in the Arctic regions of both 

 hemispheres during the Tertiary period. The only species 

 which have been able to retain a foothold in Europe are 

 R. lapponicum in Norway, R. ponticum in South Spain, 

 R. ferrugineum and R. hirsuium in the Swiss Alps. R. 

 ponticum reappears in Asia Minor, Syria, and in the 

 Southern Caucasus with R. flavum (Azalea pontica) and 

 R. caucasicum. 



R. ponticum was introduced into Ghent before 1763 

 and is of special interest as being the plant on which the 

 genus was founded and the first to become naturalised in 



