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Darwin Correspondence Project

To J. S. Henslow   27 June [1855]

Down Farnborough Kent

June 27th.—

My dear Henslow.

Very many thanks for the sermon & list of Plants,1 which though no Botanist I have been very glad to see, to get some idea of numbers of plants in a definite area. Though I modestly say I am no Botanist, I am in fact a very celebrated one, for I have just begun grasses & made out 28 species!!! which I consider a wonderful triumph.—

I return circular2 on account of misprint: you have done me & my Barnacles much honour.

And now try & be very patient for I have a heap of favours to beg. I am really anxious to know (but will not take up your time by detailing my reasons) whether you consider Lychnis diurna & L. vespertina species or varieties: their names are used by Gærtner on Hybrids:3 am I right in considering L. diurna = L. sylvestris; & L. vespertina = dioica? Judging from your old Cambridge list,4 I infer you consider them as only varieties: the London Catalogue5 & Babington6 consider them as species. If you consider them vars. will you tell me on what grounds?7

Secondly: I have become very fond of little experiments, & I mean to try whether I cannot break the constitution of plants by coloured glass picking off flowers, sowing at wrong time &c &c &c &c in a short time; & I want to know whether you can suggest any 2 or 3 hardy good seeders, which you think from presenting doubtful forms, would be interesting to try.

Thirdly. Does Geum rivale or Epilobium tetragonum grow in your neighbourhood (I do not believe either are found here, on account of our dryness) & if they do grow, would you take trouble to send me a dozen of the finest heads of each, when nearly ripe, (but not so ripe as to shed seeds) that I may count how many seeds each has for its maximum number, to compare with some very prolific hybrids, which Dr. T. Bell Salter is going to send me.—8

Lastly: busy as you are, can you forgive these several requests?— I fear I am not a little unreasonable— I want to know whether you would, & this is the most troublesome job, (though I think it sounds more troublesome than it is) sometime, say in winter or whenever you have most Leisure read over the names in the London Catalogue of Plants (& I wd. send my copy) pencil in Hand, & mark with cross, all those species, which you believe to be really species, but which are close species;—taking some such definition for a “close species”, as a form, which even to a good Botanist is a little troublesome to distinguish, or which you can just conceive possible, though not probable, that further research will prove to be only varieties.

I am really very anxious for this, but I cannot explain my motive, otherwise it might unconsciously to you influence the result.9 I do not think it would take up much more time than reading slowly over the names.—

Once again, if you can, forgive me, & believe me | My dear Henslow | Your’s most truly | C. Darwin


Henslow 1855a.
Henslow was preparing a report for the British Association for the Advancement of Science ‘On typical series of objects in natural history adapted to local museums’ (see letter from J. S. Henslow, 2 September [1854]). To this end he prepared a circular dated June 1855, entitled ‘On typical objects in natural history’, which was printed in the Report of the 25th meeting of the British Association for the Advancement of Science held at Glasgow in 1855, pp. 108–26 (Henslow 1855b). The circular was also printed separately with a slightly different title. There is a copy of Henslow 1855b in the Darwin Pamphlet Collection–CUL.
Gärtner 1849.
Henslow 1835.
H. C. Watson and Syme 1853.
Babington 1851.
CD was following up statements made in Gärtner 1849 about the reduction in fertility in crosses between different coloured forms of Verbascum and Lychnis (see letter to M. J. Berkeley, 7 April [1855], n. 8, and letter from C. C. Babington, [c. June 1855]). The subject is discussed in Natural selection, pp. 393–405, especially on p. 404.
See letter from T. B. Salter, 25 June 1855.
CD explained his reason for the request in letter to J. S. Henslow, 7 July [1855]. He had earlier asked Asa Gray to do the same (see letter to Asa Gray, 8 June [1855]).


Asks whether JSH considers Lychnis diurna and L. vespertina species or varieties.

Asks for help with his work on hybrids.

Would like JSH to go over London catalogue of British plants, marking "close species", i.e., those he considers real species but which are very closely allied. Withholds his motive as it might influence the result.

Has found Agrostis with worms in every germen and no stamens on stigma.

Now has 46 kinds of peas all growing together.

Letter details

Letter no.
Charles Robert Darwin
John Stevens Henslow
Sent from
Source of text
DAR 93: A28–A30
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 1705,” accessed on 19 July 2018,

Also published in The Correspondence of Charles Darwin, vol. 5