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Darwin Correspondence Project

To J. D. Hooker   27 July [1861]1

2. Hesketh Crescent | Torquay

July 27th

My dear Hooker

You cannot conceive how the Orchids have delighted me.2 They came safe, but box rather smashed: cylindrical old cocoa or snuff cannister much safer.— I enclose Postage.— As on account of movement I shall allude to what I suppose is Oncidium, to make certain is enclosed flower with crumpled petals this genus.—3 Also I most specially want to know what enclosed little globular brown Orchid is. I have only seen pollen of a Cattleya on a Bee,4 but surely have you not unintentionally sent me what I wanted most (after Catasetum or Mormodes) viz one of the Epidendreæ?!—5 I particularly want (& will presently tell you why) another spike of this little Orchid, with older flowers, some even almost withered, as the rostellum evidently does not come into action soon: I think only way would be to tie spike to thin elastic stick & jam stick in cannister the stick also serving to keep piece of damp blotting paper or anything else from touching the flowers. Why I want to study rostellum is that the pollen is intermediate between the two great types, as I daresay may be well known. (A) is waxy with no threads— (B) consists of a mass of pollen-grains united by elastic threads, & has exactly the structure of pollinia of Epipactis. So that (B) is in part functionally a caudicle, in structure a mass of pollen. I believe this explains the genesis of the caudicle of Orchis. By abortions of parts from this pollinium, almost any other could be made. Hence I am inclined to look at this as the prototype, & I am intensely curious to understand well the rostellum.6

Did you not think that Stelis was all in bud; I did, for the sepals were so exactly closed; but as yet, I have only one flower, that on apex, which had not been visited by some insect & had its pollinia removed. Can you tell me whence (what country) this Stelis comes, as it is so attractive to British Insects?—7

Can you easily tell me name of larger brown orchis in bud with curved peduncles? I have not yet examined it though I have worked all day.—

I grieve to hear that I cannot see an Arethusa (Vanilla belongs to same type I see in Lindley’s Veg. K.) for then I shd. have seen all great leading types.—8 You have given me intense enjoyment.—

Yours affectly & tired | C. Darwin

I am sorry to hear about death of Baby.—9 William soon joins Bank. William has been examining seeds of Groundsell,—wonderful case10

Footnotes

The year is given by the Darwins’ stay in Torquay from 2 July to 26 August 1861 (see ‘Journal’; Appendix II).
CD had asked Hooker to supply him with several orchid species that he had not yet examined (see letter to J. D. Hooker, 17 [July 1861]).
See Orchids, pp. 192–3, where the ‘depression’ or movement of the pollinium of Oncidium is described. According to CD’s view, this mechanism had been selected for in various orchids because it enabled them better to position the pollinia on insects and thus optimise the chances of the pollinia subsequently striking the stigmatic surface (ibid., p. 357).
Cattleya and other genera of the tribe of exotic orchids Epidendreae are described in Orchids, pp. 159– 66.
The final chapter of Orchids discusses the homologies of the flowers of orchids. In addition to tracing the gradation in the structure of the various organs such as the rostellum and the pollen-masses, CD also described what he believed to be the process by which the caudicle (the stalk on which the pollen-masses rest) was formed. The particular case mentioned in the letter is described in Orchids, p. 325.
Stelis is a genus of orchids found in tropical America and the West Indies. In Orchids, p. 167, CD described how the three sepals of Stelis racemiflora, after expanding, gradually close ‘with perfect exactness and shut up the flower, so that it is scarcely possible to distinguish an old flower from a bud’.
CD was unable to examine any living flowers of the tribe Arethuseae, to which the genus Vanilla belongs, before Orchids was published in May 1862 (Orchids, p. 269). The reference is to Lindley 1846, which went through several editions. It is not known which edition CD used, although it is likely to have been the third edition (Lindley 1853), in which the section on orchids was expanded. John Lindley was the first botanist to prepare a detailed classification of the orchid family and was an authority on orchid cultivation. Lindley divided the family into seven tribes: Malaxeae, Epidendreae, Vandeae, Ophreae, Arethuseae, Neotteae, and Cypripedeae. With the exception of one genus, Malaxis, all the British orchids are confined to the Ophreae and Neotteae.
The reference has not been traced.
Legal arrangements were being made for William Erasmus Darwin to join the Southampton and Hampshire Bank. CD had previously asked Hooker to recommend a programme to direct William’s current enthusiasm for botanical dissection (see letter to J. D. Hooker, 19 June [1861]). The ‘seeds’ (achenes) of the common groundsel, Senecio vulgaris, characterised by being covered with numerous soft, feathery tufts of hairs, are responsible for the plant’s great success in propagating rapidly and throughout the year (EB). Hooker had earlier described for CD how in this and other Compositae, the characteristics of the achenes facilitate propagation. See Correspondence vol. 8, letter from J. D. Hooker, 28 December 1860.

Summary

On orchids supplied by Kew; homologies of pollen and rostellum.

Letter details

Letter no.
DCP-LETT-3220
From
Charles Robert Darwin
To
Joseph Dalton Hooker
Sent from
Torquay
Source of text
DAR 115: 107
Physical description
4pp

Please cite as

Darwin Correspondence Project, “Letter no. 3220,” accessed on 23 February 2019, http://www.darwinproject.ac.uk/DCP-LETT-3220

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

letter