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Darwin Correspondence Project

To A. G. More   5 August [1860]1

Down Bromley Kent

Aug. 5th

My dear Sir

I am infinitely obliged for your most clearly stated observations on the Bee-orchis.2 It is now perfectly clear that something removes the pollen-masses far more with you than in this neighbourhood. But I am utterly puzzled about the footstalk being so often cut through.3 I shd suspect snails.—

I yesterday found 39 flowers & of them only 1 pollen-mass in 3 flowers had been removed, & as these were extremely much withered flowers I am not quite sure of the truth of this.— The wind again is new element of doubt.— Your observations will aid me extremely in coming to some conclusion. I hope in a day or two to receive some day-moths, on the probosces of which I am assured the pollen-masses of the Bee-orchis still adhere.—

Did you ever read Dr. Hookers paper in Philosoph. Transactions 1854 p. 259 on the curious structure of the Rostellum in Listera.4 Dr. H. is considerably mistaken about the use of the parts, but his facts are accurate; & it is following out the remarkable modification in structure & function of the rostellum, that I am so anxious to examine Spiranthes & Epipactis & indeed all orchids. The paper is really worth reading, though the facts in several respects are far more curious than Hooker suspected.— I wrote yesterday to thank you for the Epipactis.5 For the chance of your liking to look at what I have found; take a recently opened flower, drag gently up the stigmatic surface, almost any object—(the side of a hooked needle) & you will find the cap of the hemispherical rostellum comes off with a touch, & being viscid on under surface, clings to needle, & as pollen-masses are already attached to the back of the rostellum, the needle drags out much pollen. But to do this, the curiously projecting, & fleshy summits of anther-cases must at same time be pushed back slightly. Now when an insect head gets into the flower, when the flap of the labellum has closed by its elasticity, the insect would naturally creep out by the back-side of flower. And mark when the insect flies to another flower with the pollen-masses adhering to it, if the flap of labellum did not easily open & allow free ingress to the insect, it would surely rub off the pollen on the upper petals & so not leave it on stigma.— It is to know whether I have rightly interpreted the structure of this whole flower that I am so curious to see how insects act.— Small insects I daresay would crawl in & out & do nothing.—

I hope that I shall not have wearied you with these details.

With my cordial thanks | Believe me | My dear Sir | Yours truly obliged | Charles Darwin

If you would like to see a pretty & curious little sight—look to Orchis pyramidalis & you will see that the sticky glands are congenitally united into a saddle-shaped organ.— Remove this under microscope by pincers applied to footstalk of pollen-mass & look quickly at the spontaneous movement of the saddle-shaped organs, & see how beautifully adapted to seize proboscis of moth.—

Footnotes

This letter was first published in Correspondence vol. 8, transcribed from a copy on which the year is recorded (DAR 146: 390).
In Orchids, pp. 67–8, CD described an experiment performed by More on the bee-orchis (Ophrys apifera). More observed that ‘in plants growing singly both pollinia were invariably present. But on taking home several plants, from a large number growing in two places, and selecting plants which seemed to have had some pollinia removed, he examined 136 flowers: of these ten had lost both pollinia, and fourteen had lost one; so here there seems at first evidence of the pollinia having been removed by their adhesion to insects’.
‘Mr. More found no less than eleven pollinia … with their caudicles cut or gnawed through, but with their viscid discs still in their pouches, and this proves that some other animals, not insects, probably slugs, had been at work.’ (Orchids, p. 68).

Bibliography

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Hooker, Joseph Dalton. 1854a. On the functions and structure of the rostellum of Listera ovata. [Read 15 June 1854.] Philosophical Transactions of the Royal Society of London 144: 259–63.

Orchids: On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing. By Charles Darwin. London: John Murray. 1862.

Summary

Thanks for observations on bee orchid.

Comments on Hooker’s ["On the functions and structure of the rostellum of Listera ovata", Philos. Trans. R. Soc. Lond. 144 (1854): 259–64].

Discusses rostellum and describes fertilisation of Epipactis.

Letter details

Letter no.
DCP-LETT-2890
From
Charles Robert Darwin
To
Alexander Goodman More
Sent from
Down
Source of text
Royal Irish Academy (A. G. More papers RIA MS 4 B 46)
Physical description
ALS 7pp

Please cite as

Darwin Correspondence Project, “Letter no. 2890,” accessed on 20 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-2890.xml

Also published in The Correspondence of Charles Darwin, vol. 8

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