Etobotienbron ^ocietp ^otes!. 
in diameter, have the extremities of their fine leafy branches terminated with 
an umbel of large beautiful straw-coloured flowers, forming a striking contrast 
with the rich scarlet of other kinds of Rhododendron already beginning to show 
their blossoms in the same border. If the Rh. Chrysanthum had been a common 
plant in our collections, I should have thought our present one might have been 
an offspring from it and the true Caucasicum,” etc., etc., etc. 
From Withers. 
Rhodo caucasicum. a pretty spreading or decumbent Caucasian species, 
about 1 ft. high. Leaves lance-shaped, ovate or obovate, rusty beneath. 
Flowers in August, rosy outside, white within, spotted with green, more or less 
bell-shaped. There are varieties with white, rose, and pale yellow flowers. 
Rhodo chrysanthum. A dwarf Siberian shrub, with linear lance-shaped 
leaves, rusty beneath, and narrowed into a long stalk. Flowers in summer, 
golden yellow, about 1 in. across, broadly bell-shaped, in terminal clusters. 
To keep this plant in good condition, it should always have a good layer of 
Sphagnum Moss around the stems and covering the soil. 
Professor Bayley Balfour to Mr. J. C. Williams. 
_ \^th October, 1916. 
Dear Mr. Williams, —It is splendid that you and Mr. G. Loder are tackling 
Rh. caucasicum and its forms, and 1 hope you will shed light upon a complex 
problem. You have a starting point in two species—the Caucasian Rh. 
CAUCASICUM and the Siberian Rh. chrysanthum. The former white and pink 
flowered and with a fine velvety indumentum. The latter yellow flowered and 
with an inconspicuous hardly developed indumentum upon an evident reticulately 
veined leaf surface. They were species of early introduction— caucasicum 
said to be 1803, chrysanthum 1796. There were few hybridising species 
available for some years after these appeared. That they were frequently 
crossed I have little doubt, and I have as little doubt that the yellow colour of all 
the so-called caucasicum is derived from chrysanthum. Whence otherwise 
could it come ? There was of course flavum and the colour factor of flavum 
may have held in Rh. caucasicum after other influences, if they ever impressed 
CAUCASICUM, had disappeared. But the essential in all descents from 
CAUCASICUM seems to me to be that a yellow caucasicum is a hybrid. I think 
Hooker’s suggestion under t. 3422, of the Bot. Mag. is not far wrong— caucasicum 
variety straminea of the figure “ might have been an offspring from it 
(chrysanthum), and the true caucasicum.” Both bloods are in it. And you 
must remember that though Rh. chrysanthum is a rare plant—the dourest of 
the dour—-yet it does flower occasionally, as it did here this season, and that it is 
to be found in cultivation. A nice plant of it came to me this year from a 
nurser 5 unan under the name caucasicum. That the so-called caucasicum in 
cultivation is a mongrel I have had proof abundantly. Never have we got a pure 
bairn from caucasicum seed acquired in different quarters—anything from 
pink flowered to yellow flowered offspring. I have now a nice pan of it from 
7 
