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Darwin Correspondence Project

To George Bentham   22 June [1861]1

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

June 22d

My dear Bentham

Very many thanks for the specimen, which sufficed for one purpose & would hardly do, if I had a whole spike, for my other purpose.— I will write to Tenby.2 I daresay the “Supplements” may be unavoidable, but I cannot help thinking they will be a fertile source of wrong references, from which I often suffer in an outrageous manner.3

By the way I may mention one great difficulty which I have on my subject of Orchids; viz that several species, which are habitually visited by insects (moths almost certainly) never secrete within their nectaries or on the Labellum an atom of honey. I have now daily watched O. morio for 23 days and tried all sorts of devices. C. C. Sprengel and Kurr make similar statements about this and other species.4 Orchis Conopsea & some other species secrete abundantly; and this makes me so much wish to see spec. of O. pyramidalis without nectarys. C. C. Sprengel & Kurr believe that these orchids exist by an organised system of deception & that moths go on visiting them in hopes of finding nectar;5 I cannot swallow the belief of such roguery.6 Do you know whether nectar is ever secreted & reabsorbed promptly?— I am utterly puzzled: I have watched the nectaries till 1112 at night & all as dry as a bone.—

Here is a piece of presumption! I must think that you are mistaken in ranking Hab. chlorantha as a var. of H. bifolia:7 the pollen-masses & stigma differ more than in most of the best species of Orchis. When I first examined them, I remember telling Hooker that moths would, I felt sure, fertilise them in a different manner; & I have just had proof of this in moth sent me with the pollinia (which can be easily recognised) of H. chlorantha attached to its proboscis, instead of to the sides of its face, as in Hab. bifolia.—8

Forgive me scribbling this way; but when a man gets on his hobby-horse, he always is run away with.— Anyhow nothing here requires any answer; unless, indeed, you chance to have any light about the nectar.

Yours very sincerely | Chas. Darwin

P.S. | I have just received owing to your or Hooker’s kindness a copy of your Elementary Principles of Botany, which pleases him much & for which I thank either you or Hooker.—9

Footnotes

Dated by the relationship to the letter to George Bentham, 17 June [1861].
CD had asked Bentham to send him specimens of Orchis pyramidalis (see letter to George Bentham, 17 June [1861]). Bentham apparently told CD how to obtain further specimens from Tenby, South Wales (see letter to Charles Lyell, 6 August [1861]).
CD may have made the same complaint about the organisation of the Journal of the Proceedings of the Linnean Society to Bentham as he had to Joseph Dalton Hooker, (see letter to J. D. Hooker, 19 June [1861]). Bentham had recently been elected president of the Linnean Society.
Sprengel 1793, pp. 403, 404, and Kurr 1833, p. 28. There are annotated copies of both works in the Darwin Library–CUL.
Christian Konrad Sprengel discussed this point in Sprengel 1793, pp. 403–4, using the term ‘Scheinsaftblumen’ to describe these flowers. Johann Gottlob Kurr also used Sprengel’s term (Kurr 1833, p. 28). In Orchids, p. 45, CD translated the word as ‘sham-nectar-producers’.
According to CD’s views, it would be an anomaly if a few species among the orchids, which generally relied upon insect visitation to facilitate fertilisation, did not secrete any nectar to attract potential insect visitors. He believed that insects would soon learn that their efforts would not be repaid. See Orchids, pp. 44–53.
Bentham 1858, p. 512.
Frederick Bond had sent CD these specimens (see Orchids, p. 35). See the description of Habenaria bifolia in Orchids, pp. 88–91, where this point is discussed in detail.
Bentham 1861b.

Summary

Thanks GB for specimen [of Orchis pyramidalis].

Discusses a great difficulty with orchids: "Insects visit several species which never secrete an atom of honey." [See Orchids, p. 44ff.] Does GB know whether nectar is ever secreted and reabsorbed promptly?

Letter details

Letter no.
DCP-LETT-3193
From
Charles Robert Darwin
To
George Bentham
Sent from
Down
Source of text
Royal Botanic Gardens, Kew (Bentham letters: 692, 690)
Physical description
6pp

Please cite as

Darwin Correspondence Project, “Letter no. 3193,” accessed on 13 December 2018, http://www.darwinproject.ac.uk/DCP-LETT-3193

Also published in The Correspondence of Charles Darwin, vol. 9

letter