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Darwin Correspondence Project

To Thomas Rivers   8 June [1866]1

Down. | Bromley. | Kent. S.E.

June 8th

My dear Sir

I thank you most cordially for the Cytisus, after examining which I forwarded to Prof. Caspary at Kœnigsberg;2 so you have killed two birds with one act of kindness. The C. adami case gets more & more perplexing. I wish your experiments with the buds of the Negundo had succeeded.—3 If you will not think me an insufferable bore, I wish you wd. observe whether Cytisus purpureus-elongatus produces any pods & inform me:—4

With many thanks | My dear Sir | Yours very sincerely | Ch. Darwin


The year is established by the relationship between this letter and the letter from Thomas Rivers, 6 June 1866.
See letter from Thomas Rivers, 6 June 1866. CD was interested in Robert Caspary’s research on Cytisus adami (now +Laburnocytisus adami). See letter to Thomas Rivers, 27 April [1866] and n. 4.
See letter from Thomas Rivers, 6 June 1866 and n. 3. CD cited Rivers on the transmission of colour from the bud of a purple-leaved hazel to a rootstock of the common green-leaved hazel in Variation 1: 395.
See letter from Thomas Rivers, 6 June 1866 and n. 2. In Variation 1: 388–90, CD discussed the viability of ovules and pollen in Cytisus hybrids, and reported a case of a sterile hybrid of Cytisus purpureus and C. elongatus that had been described by Alexander Carl Heinrich Braun (see Braun 1853, p. xxiii).


Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


Examined the Cytisus and forwarded to Caspary. The C. adami case "gets more and more perplexing", asks for report if Cytisus purpureus-elongatus produces any pods.

Letter details

Letter no.
Charles Robert Darwin
Thomas Rivers
Sent from
Source of text
John Wilson (dealer) (Catalogue 63)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5115,” accessed on 27 January 2022,

Also published in The Correspondence of Charles Darwin, vol. 14