Kt)t 3Evf)otiotJEni3ron ^ocietp ^otesl. 
RHODODENDRONS AT DAWYCK, TWEED-DALE. 
Contributed by F. R. S. Balfour. 
Dawyck House stands about 750 feet above sea level, in the upper reaches of 
the Tweed ; the whole range of lofty hills where the Clyde and Tweed take their 
rise is perhaps the coldest region in the island. 
The formation is old silurian and the drainage very free, the soil in which 
the Rhododendrons are planted is a mixture of leaf-mould and black peaty 
humus found in the park, but which requires a considerable admixture of river 
sand to make it workable. 
The rainfall varies from 35 to 45 inches, and is remarkably evenly distributed 
over every month of the year. 
The experience of the last two years has only confirmed what I have knovni 
for long : that it is vain to attempt to grow successfully at Dawj^ck any but the 
hardier species. On several occasions in both winters there were 34 degrees of 
frost, and the temperature fell to zero as late as on 1st April, 1917. 
There are large masses of the older Rhododendron hybrids, also R. maximum, 
pure or nearly so, planted many years ago. Recent plantings have been made 
in a sheltered, wooded glen in the form of separate collections of the species of 
different regions. 
European as weU as North American (excepting R. carolinianum) and 
Caucasian species flower abundantly, none better than R. californicum 
among the American, and R. Smirnowi among the Caucasian species. The 
rare Western American R. albiflorum (Hooker) flowered particularly well this 
year and set seed. 
The Chinese species, with the exception of a few good-sized plants from 
Wilson’s earlier expeditions, were all grown from seed collected by him in his 
last two expeditions undertaken for the Arnold Arboretum. Of these I lost the 
following during the last two years :— 
R. Augustinii, R. Delavayi, R. floribundum, R. Hunnewellianum, 
R. HYPOGLAUCUM, R. INTRICATUM, R. IRRORATUM, R. LUTESCENS, R. 
neriiflorum, R. Watsonii. 
While the following suffered more or less :— 
R. argyrophyllum, R. argyrophyllum var. cupul.4re, R. chartophyllum, 
R. lacteum, R. micranthum, R. polylepis, R. taliense, R. villosum, R. 
yunnanense. 
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