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Darwin Correspondence Project

To Mary Treat   12 August 1873

Down, | Beckenham, Kent. [Bassett, Southampton.]

Aug. 12. 1873

Dear Madam

I am very much obliged to you for having so kindly sent me an account of Drosera filiformis.1

Your statements will be very useful to me in my short account of this species. I am familiar with what you state about D. longifolia & rotundifolia.2

I have just lately been working hard for the last 2 months on the latter species; & before long shall draw up an account of their digestive powers & action under various stimulants.3 If I were in your place I should be afraid to publish the statement about the Drosera bending towards flies or meat which they did not touch; unless I had tried the experiment many times, under the most rigorous precautions; for I am convinced that no botanist wd believe the statement unless all the precautions taken were described in detail.

With my best thanks, I remain dear Madam | yours faithfully & obliged | Ch. Darwin

Whenever my little book is published I will do myself the pleasure to send you a copy; it will be on the genera Drosera, Dionæa & Drosophyllum with a republication of my paper on Climbing Plants.4


See letter from Mary Treat, 28 July 1873 and n. 2. Treat had revised her opinion on the size of insects that were captured by Drosera filiformis (the thread-leaved sundew).
Drosera longifolia is now classified as two species, D. anglica (the great sundew) and D. intermedia (the spoonleaf sundew). In Insectivorous plants, p. 278, CD, in referring to Treat’s account, described D. longifolia as ‘a synonym in part of Drosera anglica’. Treat probably observed D. intermedia, the species native to her home state, New Jersey (see Schnell 2002, pp. 261–2; 268–9, for the distribution of both species in North America). Drosera rotundifolia, the common or round-leaved sundew, was the species that CD used for most of his experimental work.
For CD’s account of his experiments on Drosera rotundifolia, see Insectivorous plants, pp. 1–277.
Insectivorous plants was published in July 1875; Climbing plants 2d ed. was published in November 1875 (Freeman 1977). Treat’s name appears on CD’s presentation list for Insectivorous plants, but not on his list for Climbing plants 2d ed. (DAR 210.11: 29).


Climbing plants 2d ed.: The movements and habits of climbing plants. 2d edition. By Charles Darwin. London: John Murray. 1875.

Freeman, Richard Broke. 1977. The works of Charles Darwin: an annotated bibliographical handlist. 2d edition. Folkestone, Kent: William Dawson & Sons. Hamden, Conn.: Archon Books, Shoe String Press.

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


Thanks MT for information on Drosera filiformis [see 8989].

Warns her against publishing statement about Drosera bending towards flies or meat that they have not touched.

Will send his book [Insectivorous plants] when published.

Letter details

Letter no.
Charles Robert Darwin
Mary Lua Adelia (Mary) Treat
Sent from
Source of text
Vineland Historical and Antiquarian Society
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 9005B,” accessed on 21 January 2022,

Also published in The Correspondence of Charles Darwin, vol. 21