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Darwin Correspondence Project

To Thomas Rivers   27 April [1866]1

Down. | Bromley. | Kent. S.E. [6 Queen Anne Street, London]

April 27th

My dear Sir

From reading your last article in Journal of Hort. I am going to beg a favour; & favours you have always granted me at least twice over.— It is to make a memorandum, & send me, when partially in flower, a raceme of Cytisus purpureus-elongatus. & at same time, if you have it, a raceme of C. Adami.—2 My tree of latter is dead, but I could probably get flowers by sending to Westerham;3 yet I shd. prefer flowers from you, for then I shd. have them fresh at same time with those of C. purp-elongatus. These flowers ought to be enclosed in tin-foil or in very small tin-cannister & sent by Post.—

Why I want them is that Prof. Caspary states that in C. Adami the pollen in appearance is good, whilst the ovules are bad. Now this does not occur in any known sterile ordinary hybrid, & Caspary hence argues that C. Adami is not a common hybrid. So that I am very curious to examine pollen & ovules of C. purp-elongatus; as I likewise will of Watererer’s supposed hybrid between C. laburnum & alpinus.—4

Mr Robson does not know what he is talking about & in how odious a spirit he answered you.—5

If you will kindly grant me the above favour, do not trouble yourself to write, but when time comes send me the flowers to dissect. My health at last is better, & I am able to do a little work.

My dear Sir | yours sincerely | Ch. Darwin


The year is established by the relationship between this letter and the letter from Thomas Rivers, 17 May 1866.
Rivers’s article on fruit culture in the Journal of Horticulture for 24 April 1866 mentioned shields of Cytisus purpureus and a specimen of ‘Cytisus purpureus elongatus’ that Rivers had in his own nursery garden (Rivers 1866b, p. 306). ‘Cytisus purpureus elongatus’, described by Rivers as a distinct variety, was a hybrid between C. purpureus and C. elongatus, but is not recognised in modern taxonomy. C. adami is now +Laburnocytisus adamii.
The florist, nurseryman, and seedsman John Cattell had premises at Westerham, Kent (R. Desmond 1994, Post Office directory of the six home counties 1859–66).
On CD’s interest in Robert Caspary’s paper on graft hybrids such as Cytisus adami (Caspary 1865a), see the letter to Asa Gray, 16 April [1866] and n. 14. CD described the ovules and pollen-grains of ‘Cytisus purpureo-elongatus’ in Variation 1: 389. He described ‘Waterer’s laburnum’ in Variation 1: 390, reporting that his specimen, though usually infertile, yielded some good seeds in 1866. The species is now known as Laburnum x watereri, a hybrid of L. alpinum and L. anagyroides.
Rivers had criticised an article by John Robson in the Journal of Horticulture on the grafting of trees and shrubs (Robson 1866a), in particular Robson’s claim that the budding or grafting of a purple Cytisus onto the common Laburnum produced a staining of the bark and foliage (see Rivers 1866a). Robson defended his claim in a subsequent issue of the journal (Robson 1866b), prompting a further reply from Rivers (Rivers 1866b).


Desmond, Ray. 1994. Dictionary of British and Irish botanists and horticulturists including plant collectors, flower painters and garden designers. New edition, revised with the assistance of Christine Ellwood. London: Taylor & Francis and the Natural History Museum. Bristol, Pa.: Taylor & Francis.

Post Office directory of the six home counties: Post Office directory of the six home counties, viz., Essex, Herts, Kent, Middlesex, Surrey and Sussex. London: W. Kelly & Co. 1845–78.

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


Asks for racemes of Cytisus purpureus-elongatus and C. adami for comparison, because Robert Caspary argues that C. adami is not a common hybrid.

Letter details

Letter no.
Charles Robert Darwin
Thomas Rivers
Sent from
London, Queen Anne St, 6
Source of text
Remember When Auctions (Cat. 41)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5070,” accessed on 8 May 2021,

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