To G. H. K. Thwaites 30 March [1863]1
Down. | Bromley. | Kent. S.E.
March 30th
My dear Mr Thwaites
I thank you most cordially for the specimens which have interested me exceedingly.2 The Sethia is a beautiful case of what I shall call “reciprocal dimorphism”: unfortunately all the anthers were knocked off the long-styled, so I could not compare pollen, except from a bud in which pollen was not mature, & I dare not trust my measurements.3 If you were to watch insects visiting these flowers I would wager that you would see body dusted by long stamens, & probosis by short anthers; & the object of unequal length of the alternate stamens is to get pollen on to proboscis from more than a pair of anthers; in short to rake them. I judge this from what I have seen in Lythrum.4 Are there any Lythraceæ in Ceylon; you would be likely to find three forms, reciprocally related in sexual functions, in this order; & with two kinds of pollen in each flower. If you observe any more facts, I shd. be grateful for information & specimens. I have also been very glad to see the Limnanthemum: it, also, is a very pretty case.5 I have got a hot-house: could I grow it? & if so, could you send me seed?6
Any flower with half anther of one colour & half of other colour (if not due to abortion of one set) probably indicates dimorphism or trimorphism.—7
I much wish to experiment on one plant in each order.— Sethia I presume is a tree.
I will soon send you a little paper on dimorphism of Linum.—8
Thank you for telling me about Discospermum; it is an important fact.—9
You have hit the nail on the head in supposing that I am interested about galls (& what curious ones those are that you have sent me!); but I unfortunately know hardly anything about them; nor do I know where I can find any full account. The subject is most curious, & I have often reflected on it, & at one time thought I would attempt a series of experiments. It is truly wonderful what a change a little poison or irritation has effected, & effected in so diversified a manner.—10
With respect to the curious specimens, which you so kindly have sent me of Gomphia & Lasemia, I do not know what to think.11 Are they not the effect of insect puncture or disease, like those we see on our Birch-trees? I shd. fear to class them with what gardeners’ call “sports” or bud variation. Can you illuminate me?
With cordial thanks | Dear Thwaites | Yours very sincerely | C. Darwin
Footnotes
Bibliography
Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.
Forms of flowers: The different forms of flowers on plants of the same species. By Charles Darwin. London: John Murray. 1877.
General index to the Journal of the Linnean Society: General index to the first twenty volumes of the Journal (Botany), and the botanical portion of the Proceedings, November 1838 to June 1886, of the Linnean Society. London: Linnean Society of London. 1888.
‘Two forms in species of Linum’: On the existence of two forms, and on their reciprocal sexual relation, in several species of the genus Linum. By Charles Darwin. [Read 5 February 1863.] Journal of the Proceedings of the Linnean Society (Botany) 7 (1864): 69–83. [Collected papers 2: 93–105.]
Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.
Summary
Thanks GHKT for specimens of Sethia. Discusses functions of their dimorphism for insect fertilisation.
Discusses polymorphism and fertilisation in Lythraceae.
Asks for seed of Limnanthemum.
Describes his interest in galls.
Discusses curious specimens of Gomphia and Lesemia.
Letter details
- Letter no.
- DCP-LETT-4067
- From
- Charles Robert Darwin
- To
- George Henry Kendrick Thwaites
- Sent from
- Down
- Source of text
- American Philosophical Society (Mss.B.D25.293)
- Physical description
- ALS 4pp
Please cite as
Darwin Correspondence Project, “Letter no. 4067,” accessed on 26 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-4067.xml
Also published in The Correspondence of Charles Darwin, vol. 11