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REPORT UPON RHODODENDRON CAUCASICUM AND 
ITS HYBRIDS. 
It will be remembered that at a meeting of the Rhododendron Society, held 
on October 12th, 1916, it was decided that a small Committee should be appointed 
to enquire as to the known forms of pure Rhododendron caucasicum species ; 
and secondly, as to what hybrids of interest have been raised, and why the work 
was given up. Messrs. J. C. Williams and G. W. E. Loder consented to report 
upon the species, and Sir Edmund Loder agreed to deal with the hybrids. 
With regard to Rhododendron caucasicum, attention is naturally dravm to 
this species and to its hybrids, by the Rhododendron which perhaps gives pleasure 
to the greatest number of people of all the countless Rhododendron species and 
hybrids, namely, Rh. Nobleanum. 
Readers of gardening books and papers, and visitors to gardens in the different 
parts of the country, will have been struck by the evidence that R. caucasicum 
flowers early in the year, and again late in the year, also by the wide area over 
which it is grown. They will probably have noticed the evidence in many 
places of considerable work by hybridisers in former days, whilst in recent times 
it has been abandoned. The hybrids we know well from this cross all hold their 
own and rather more, and there is none of the harshness in colour which is so 
often the brand of the catawbiense crosses. 
The caucasicum species and many of its hybrids have a few very marked 
features common to most of them. In the first place, the very erect form of the 
seed truss, also the readiness with which most of them will strike from cuttings, 
compared with other large leaved varieties (an instance of which, with regard 
to Cunningham’s white, is given by Mr. Watson, on page 72 of his book, in the 
“ Present-Day Gardening ” series). There is a strong tendency to produce a 
yellow strain in their colouring, of which there are many forms ; and also the 
inclination, referred to above, to give flower in the autumn as well as in the 
spring. Further, the varieties which are apparently nearest to the true species, 
ripen their seed earlier than any other Rhododendron, in some cases the pod 
will burst in July. 
The following hybrids, not yet in commerce, have been raised by Messrs. 
Cunningham & Fraser :— 
Caucasicum x campylocarpum. 
Caucasicum x Thompsoni. 
Cunningham’s sulphur x campylocarpum. 
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