Cfte i^fjobobenbron ^ocietp ^otesi. 
Petrograd seeds, of which I have hopes, and that I may see the true caucasicum 
at last. Further evidence of its hybrid character is to be found in the 
indumentum. Not one of the plants that we have had as caucaSicum has 
typical CAUCASICUM indumentum. All of them show an approach to 
CHRYSANTHUM. Apart from the indumentum the somatic characters of culti¬ 
vated CAUCASICUM are more those of caucasicum than of chrysanthum. 
Perhaps rosa-mundi is the most chrysanthoid in body of the named hybrids, 
and it is essentially caucasicoid in flower. 
Bot. Mag., tab. 1145, is a curious plant. No true caucasicum has a venation 
such as is shown on the leaves of the illustration. The plant recalls several 
unnamed hybrids which have been in cultivation for half a century here. 
To your question then : How many forms of caucasicum are in cultivation ? 
I would answer—to my knowledge, none ! There are only hybrids. 
In illustration of the mixed progeny that comes from caucasicum, here is a 
scheme based upon what I have learned from Mr. Fraser, of Cunningham and 
Fraser :— 
CAUCASICUM 
(yellow) 
I gather that the caucasicum white .4 rboreum cross gave dominant white 
Nobleanum and recessive Cunningham’s sulphur. 
The female parent in all was evidently the hybrid, not the true pink 
CAUCASICUM. This you will recognise is most important. 
Mr. Fraser teUs me that all these caucasicum crosses give fertile seed and 
breed true. Certainly Cunningham’s sulphur comes true from seed, and 
probably it is recollection of comment upon this that has left the impression 
upon your mind of its being a true species.* It seems to me that here as in others 
of these long cultivated plants, a new record will have to be begun if we are to 
solve the problem of their real relationships. Systematic breeding from plants 
raised from seed of undoubted true wild species must be carried out. 
ISAAC BAYLEY BALFOUR. 
Professor Bayley Balfour to Mr. J. C. Williams. 
Royal Botanic Garden, Edinburgh 
28//j October, 1916. 
Dear Mr. Williams, —The seedling caucasicums have reached you, I am 
glad to hear, and I hope are to prove to be the true species. Their source is 
promising. I hope I have not misled you about Rh. chrysanthmn, by speaking 
of it as Siberian. I did not intend to convey that chrysanthum is limited in 
distribution to Siberia. Its spread is geographically and phyletically interesting. 
* Cunningham’s yellow at the Edinburgh Botanical Gardens having been 
found there to come true from seed, it is possibly a true species.—J.C.W. 
8 
