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Darwin Correspondence Project

To J. D. Hooker   19 [June 1860]1

Down

19th

My dear Hooker

Have pity on me & let me write once again on Orchids for I am in a transport of admiration at most simple contrivance, & which I shd. so like you to admire.2 How I wish I was a Botanist.3 Such brief books as I have, say structure of Gymnadenia like Orchis, but I find the stigma consists of two most curious lateral horns;4 I must think these horns are the stigma, from what follows— push thick needle down mouth of nectary & the two pollen masses adhere by thin long naked strap-shaped sticky glands, & then when needle withdrawn by elasticity become nearly parallel to needle. In doing this not a grain of pollen is left on the horn-like stigma— But here comes pretty fact, hold needle in same relative position to parts of flower & push into nectary of another flower, & lots of grains of pollen are almost inevitably left on the two humid stigmas. In fact G. conopsea would hardly ever get a grain of pollen of its own flower!5 I was led to observe this by finding that the 13 pollen-masses on the proboscis of Acontia luctuosa belonged to this orchis.—6

I see Bentham puts this plant into genus Orchis, but surely such a difference in stigma, & naked & curious strap-formed glands must be good generic character.7 If, as is likely, you do not care or are too busy to look at this, as it seems to me really beautiful relation of part, ask Mr Bentham, whether he will.—8 I see the stigmatic horns rise from spot where stigma lies in true Orchis.

C. D.

Etty decidedly rather better.9

(I vow I will not bore you again.)

Footnotes

The date is established by the relationship between this letter and the letter to J. D. Hooker, 26 [June 1860] (Correspondence vol. 8).
Orchids had been a frequent topic in CD’s correspondence with Hooker since April 1860 (see Correspondence vol. 8; see also his questions on orchids to the readers of Gardeners’ Chronicle (Correspondence vol. 8, letter to Gardeners’ Chronicle, [4–5 June 1860]).
In his letters to Hooker, CD had long been scornful of his own botanical capability (see, for example, Correspondence vol. 3, letter to J. D. Hooker, [3 September 1846]). In later life, CD claimed that, while at Cambridge, he attended John Stevens Henslow’s botanical lectures and excursions as an amateur and ‘did not study botany’ (Autobiography, p. 60).
CD was evidently observing the reproductive organs of either Gymnadenia conopsea, which he described in Orchids, pp. 79–82, or G. albida, which he described in Orchids, pp. 82–3. One of the books to which CD may have referred is Bentham 1858 (see n. 7, below); there is a lightly annotated copy in the Darwin Library–CUL (see Marginalia 1: 51).
CD’s experiment imitated the insertion of the proboscis of a moth or butterfly into the flower. In the introduction to Orchids, CD stated that a principal object of the book was to show that flowers in that family have adapted to assist cross-fertilisation, thereby challenging earlier texts, for example Sprengel 1793, that described orchids as being generally self-fertilised (Orchids, pp. 1–3). In the conclusion, CD wrote, ‘Nature thus tells us, in the most emphatic manner, that she abhors perpetual self-fertilisation’ (Orchids, p. 359).
The moth Acontia luctuosa was also listed in Orchids, p. 36, with twenty-two other lepidopterous species, as having been observed with pollinia of Orchis pyramidalis adhering to its proboscis.
The reference is to Bentham 1858, in which the fragrant orchid, Gymnadenia conopsea, is classified as Orchis conopsea, and G. albida as Habernaria (now Habenaria) albida (Bentham 1858, pp. 511–12). The morphological differences between Orchis and Gymnadenia, noted in Bentham 1858, p. 511, did not include their stigmas or the sticky glands of their pollinia. See also n. 4, above.
George Bentham had been compiling Genera plantarum with Hooker since 1857 (Allan 1967, p. 213). From that year, Bentham went regularly to Kew to collaborate with Hooker (Bentham 1883, p. 305).
On Henrietta Emma Darwin’s recurrent ill health between 1857 and 1861, see Bowlby 1990, pp. 329–30, 354, 359–60. In April 1860, she contracted either typhus or typhoid fever (Correspondence vol. 8, letter to J. D. Hooker, 11 May [1860] and n. 5).

Summary

CD writes of his admiration for pollination contrivances in Gymnadenia. Ask George Bentham whether this plant should be removed from genus Orchis.

Letter details

Letter no.
DCP-LETT-3290
From
Charles Robert Darwin
To
Joseph Dalton Hooker
Sent from
Down
Source of text
DAR 261.10: 69 (EH 88206052)
Physical description
2pp

Please cite as

Darwin Correspondence Project, “Letter no. 3290,” accessed on 16 September 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-3290.xml

Also published in The Correspondence of Charles Darwin, vol. 13 (Supplement)

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