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Darwin Correspondence Project

To W. T. Thiselton-Dyer   23 June 1874

Down, | Beckenham, Kent.

June 23rd. 1874

My dear Mr Dyer

I wrote to you abt a week ago, thanking you for information on cabbage seeds, asking you the name of a Luzula or Carex, & on some other points; & I hope before very long to receive an answer.1 You must now, if you can, forgive me for being very troublesome for I am in that state in which I would sacrifice friend or foe. I have ascertained that bits of certain leaves, for instance Spinach, excite much secretion in Pinguicula, & that the glands absorb matter from the leaves.2

Now this morning I have received a lot of leaves from my future daughter-in-law in North Wales, having a surprising number of captured insects on them, a good many leaves, & two seed capsules.3 She informs me that the little leaves had excited secretion; & my son4 & I have ascertained this morning that the protoplasm in the glands beneath the little leaves has undoubtedly undergone aggregation. Therefore, absurd as it may sound, I am prepared to affirm that Pinguicula is not only insectivorous but graminvorous & granivorous! Now I want to beg you to do is to look under the simple microscope at the enclosed leaves & seeds, & if you possibly can tell me their genera.5 The little narrow leaves are remarkable; they are fleshy with the edges much curled from the axis of the plant and bear a few long glandular hairs; they grow in little tufts. These are the commonest on Pinguicula, & seem to afford most nutritious matter. A second leaf is like a miniature sycamore. With respect to the seeds; I suppose that one is a Carex,; the other looks like that of Rumex, but is enclosed in a globular capsule. The Pinguiculæ grew on marshy low mountainous land. I hope you will think this subject sufficiently interesting to make you willing to aid me as far as you can.

Any how forgive me for being so very troublesome, & believe me to be Yrs very sincerely | Ch. Darwin


See Insectivorous plants, p. 385. In a note about this experiment dated 16 June 1874, CD concluded that Pinguicula (butterwort) exuded ‘far more secretion from spinach than cabbage’ (DAR 59.1: 56v).
In his account of the observations he made on this set of specimens sent by Francis Darwin’s fiancée, Amy Ruck, CD described them as having been sent by ‘a friend’ (Insectivorous plants, p. 369). CD’s experimental notes are in DAR 59.1: 57 and 60–1.
For Thiselton-Dyer’s response, see his letter of 26 June 1874.


Insectivorous plants. By Charles Darwin. London: John Murray. 1875.


Has found Pinguicula excited by bits of leaves; appears to digest leaves and seeds. Plant not only insectivorous but graminivorous. Asks WTT-D to identify seeds.

Letter details

Letter no.
Charles Robert Darwin
William Turner Thiselton-Dyer
Sent from
Source of text
Royal Botanic Gardens, Kew (Thiselton-Dyer, W. T., Letters from Charles Darwin 1873–81: 12–13)
Physical description
LS(A) 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 9508,” accessed on 13 April 2024,

Also published in The Correspondence of Charles Darwin, vol. 22