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Darwin Correspondence Project

To Asa Gray   28 May [1864]1

Down Bromley Kent

May 28th

My dear Gray

Your kindness will make you glad to hear that I am nearly as well as I have been of late years, though a good deal weaker. I have been slowly writing a paper on Lythrum,2 & this has disinclined me for the exertion of writing letters. It has been so pleasant doing a little work after 8 months inaction. Speaking of Lythrum reminds me to say that your Nesæas are looking very healthy, & Mitchella moderately so.3 Some time ago I received Dr. Wrights letter about Orchids:4 if you write to him, beg him to note what attracts insects to Begonias? do they gnaw or penetrate the petals? Also, but I care less, what attracts them to Melastomas?5 Poor Dr. Cruger of Trinidad, who promised to observe, is dead.—6

Whenever my Lythrum paper is printed I will of course send you a copy,7 & I shall like to hear whether you think it as curious a case as I do.— I have got another new sub-class of dimorphic plants.—8

An Irish nobleman on his deathbed declared that he could conscientiously say that he had never througout life denied himself any pleasure; & I can conscientiously say that I have never scrupled to trouble you.— So here goes.— Have you travelled south, & can you tell me, whether the trees, which Bignonia capreolata climbs, are covered with moss, or filamentous lichen or Tillandsia; I ask because its tendrils abhor a simple stick, do not much relish rough bark, but delight in wool or moss.9 They adhere in curious manner, by making little disks at end of each point, like the Ampelopsis; when the disk sticks to bundle of fibres, these fibres grow between them & then unite, so that the fibres of wool end by being embedded in middle: By the way I will enclose some specimens & if you think it worth while you can put them under the simple microscope. It is remarkable how specially adapted some tendrils are; those of Eccremocarpus scaber do not like a stick, will have nothing to say to wool; but give them a bundle of culms of grass or bundle of bristles & they seize them well.—10

I have been reading with great interest von Mohls paper in Bot. Zeitung on imperfect self-fertile flowers.11 He quotes you that perfect flowers of Voandzeia are quite sterile—12 How is this known, for is it not a Madagascar plant?13 I presume you know that wild plants of Amphicarpea are generally sterile.14 How I shd. like to have seed to ascertain whether this plant is sterile when fertilised.— What a curious analogous case is that of Leersia: I have just got plants of this grass.—15 Please remember, if you ever come across it, seeds of the Campanula perfoliata.—16

Lastly (God forgive me) can you tell me whether any of your Hollies are in state of Thyme viz some plants hermaphrodites & some Females: I have a dimorphic case which, I think, will show how this state of Thyme &c arises.—17

Do you see the Reader: it is the best newspaper for science ever published in England: there was lately a capital article in it by Wallace.18 He has, also, published lately in the Anthropological Review a short, but most suggestive article on the natural selection of Man.—19

When inclined, do write & tell me a little about yourself & what you are doing. Is the museum for your Herbarium settled?20 I hope sincerely that my former fellow-sufferer Mrs. Gray is quite well again.—21 What utter misery the stomach causes!— As for public news I am much in arrear, for I gave up for months hearing the newspaper, as I found it more fatiguing than novels. I have heard during late 9 months an astounding number of love scenes.—

What dreadful carnage you have just recently suffered.—22 What will the end be? Will slavery perish, if so the cost is not too dear?

Farewell my dear & good friend. You will see that I have regained my ten-horse-interrogoratory-power:—farewell— yours most sincerely | C. Darwin

I send a Photograph of myself with my Beard. Do I not look venerable?23


The year is established by CD’s reference to his work on the manuscript of ‘Three forms of Lythrum salicaria (see n. 2, below).
CD finished the manuscript of ‘Three forms of Lythrum salicaria about 25 May 1864 (see ‘Journal’ (Correspondence vol. 12, Appendix II)); it was read at the Linnean Society on 16 June 1864. A draft of the manuscript, together with notes for the paper, is in DAR 27.2. For a summary of CD’s work on Lythrum, see Correspondence vol. 12, Appendix III. See also letters to J. D. Hooker, 13 April [1864] and n. 7, and 22 [May 1864] and n. 16.
Gray sent CD Nesaea seeds with his letter to CD of 27 October 1862 (Correspondence vol. 10), and Mitchella plants by way of James Anderson (see Correspondence vol. 10, letter from Asa Gray, 9 December 1862, and letter to James Anderson, 23 December [1862]). CD described the plants raised from the seeds of the trimorphic species Nesaea verticillata (a synonym of Decodon verticillatus, swamp loosestrife) in ‘Three forms of Lythrum salicaria, p. 191 (Collected papers 2: 125), and Forms of flowers, p. 167. The flowers produced by Mitchella repens, a dimorphic species, and CD’s experiments with them in 1864 and 1865, are described in Forms of flowers, pp. 125–7. CD’s notes on these experiments, beginning in July 1864, are in DAR 110: B84–6 and B88–93.
Gray did not write a letter since Wright was due to visit him in July (see letter from Asa Gray, 11 July 1864). No letter from Wright responding to CD’s queries has been found. For CD’s many inquiries into the habits of insects visiting flowers of the family Melastomataceae see, for example, letter from A. R. Wallace, 2 January 1864 and n. 13.
CD refers to Hermann Crüger, director of the Botanic Garden, Trinidad. See letter from J. D. Hooker, 20 April 1864, and letter to J. D. Hooker, 25 April [1864] and n. 6.
‘Three forms of Lythrum salicaria was published in the part of the Journal of the Linnean Society (Botany) that was issued to members of the society on 12 December 1864 (General index to the Journal of the Linnean Society, p. vi). CD arranged for additional copies to be dispatched in mid-December 1864 (see letter to Daniel Oliver, 15 December [1864]). Gray’s name appears on CD’s presentation list for this paper (see Correspondence vol. 12, Appendix III); Gray acknowledged receipt of the paper in his letter to CD of 17 January 1865 (Correspondence vol. 13).
In Gray 1862b, p. 419, Gray divided dimorphism into two classes, ‘diœcio-dimorphism’ (now called heterostyly), and ‘precocious fertilization’ (now called cleistogamy). CD had long been investigating a third class of dimorphism that he later called ‘gyno-dioecism’, in which plants have female flowers and flowers of an ordinary hermaphrodite form on different plants (see, for example, Correspondence vol. 11, letter to W. E. Darwin, [5 May 1863] and n. 6). For CD’s observations on gyno-dioecism in 1864 see the letter to W. E. Darwin, 14 May [1864]. See also n. 17, below. CD discussed gyno-dioecious plants in Forms of flowers, pp. 298–309.
CD’s experiments with Bignonia capreolata and wool are recorded in a note dated 24 May [1864] in DAR 157.1: 140. Gray confirmed CD’s hypothesis that B. capreolata was adapted for climbing moss-covered or lichen-covered trees (see letter from Asa Gray, 11 July 1864 and n. 5, and ‘Climbing plants’, pp. 56–9). See also letter to J. D. Hooker, 4 December [1864] and n. 13.
CD discussed the diverse activities of tendrils that had adapted to particular conditions of climbing in ‘Climbing plants’, illustrating his case with reference to Bignonia capreolata on pp. 56–9 and 103–4, Ampelopsis on pp. 84–7 and 104, and Eccremocarpus on pp. 60–1 and 102–5. CD’s notes on Ampelopsis hederacea (Virginia creeper) dated July and August [1864] are in DAR 157.2: 65–7, and his notes on Eccremocarpus scaber, dated between March and June 1864, are in DAR 157.2: 1–4.
CD refers to Hugo von Mohl’s article discussing dimorphism and cleistogamy in Botanische Zeitung (Mohl 1863); there is an annotated copy of this paper in the Darwin Pamphlet Collection–CUL. Mohl claimed that the existence of self-pollinating flowers contradicted CD’s assertion in Orchids, p. 359, that ‘nature … abhors perpetual self-fertilisation’ (Mohl 1863, p. 325). CD’s attention had been drawn to the article by Daniel Oliver, who subsequently published a review of it (see Correspondence vol. 11, letter from Daniel Oliver, 27 November 1863, and letter to Daniel Oliver, 28 [November 1863], and [Oliver] 1864). See also this volume, letter from Hermann Crüger, 21 January 1864 and n. 22, and letter to J. D. Hooker, 5 April [1864] and n. 22. CD discussed Mohl’s criticisms in ‘Three forms of Lythrum salicaria, pp. 191–2 n. (Collected papers 2: 130–1 n. 15).
The reference is to Mohl 1863, p. 312; however, Gray did not make this statement; see letter from Asa Gray, 11 July 1864.
Voandzeia is a genus in the family Leguminosae with one species occurring in tropical Africa and Madagascar (Willis 1973). See also letter from Asa Gray, 11 July 1864.
For CD’s published discussion of Amphicarpaea see ‘Three forms of Lythrum salicaria, p. 192 n. (Collected papers 2: 131 n. 15). The genus Amphicarpaea is also discussed in Forms of flowers, p. 327, as one of three genera in the family Leguminosae whose cleistogamic flowers are produced on subterranean stems.
See letter from William Bennett, 25 May 1864; the reference is to Leersia oryzoides. CD’s interest in this species had been stimulated by Daniel Oliver’s article on dimorphic flowers ([Oliver] 1864a). See letter to J. D. Hooker, 13 April [1864] and nn. 9–10, and letter from William Bennett, 29 April 1864, n. 4.
Gray sent specimens of Campanula perfoliata (Specularia perfoliata) in 1863; however, CD put the specimens in warm water to soak the flowers before he realised that they had seeds. Evidently the seeds failed to germinate (see Correspondence vol. 11, letter from Asa Gray, 7 July 1863, and letter to Asa Gray, 4 August [1863]). CD was interested in this North American species, now known as Triodanis perfoliata, because it bears cleistogamic flowers (see Forms of flowers, p. 330).
CD refers to the dimorphic species Pulmonaria angustifolia, which he thought might represent a transition from heterostyly to what he later called ‘gyno-dioecism’, in which species include both hermaphrodite and female individuals on different plants (see letter to W. E. Darwin, 14 May [1864] and nn. 8 and 14). CD’s notes on hollies, dated 18 May 1864, are in DAR 109: A8. CD discussed hollies (Ilex) and Thymus in Forms of flowers, pp. 297–304; Gray is cited for information on Ilex opaca on p. 298.
CD refers to the Reader, a weekly review of literature, science, and the arts. For a discussion of the character of the Reader and the composition of its editorial board, see letter to J. D. Hooker, 26[–7] March [1864] and n. 17. CD also refers to Alfred Russel Wallace’s article on butterflies of the Malay Peninsula published in the Reader on 16 April 1864, pp. 491–3; the article was an abstract of the paper he had prepared for the Linnean Society (Wallace 1864a; see letter from A. R. Wallace, 10 May 1864 and n. 8).
CD refers to Wallace 1864b. See letters from A. R. Wallace, 10 May 1864 and nn. 5–7, and 29 May [1864], and letter to A. R. Wallace, 28 [May 1864].
Jane Loring Gray had been particularly unwell during the winter of 1863–4. See Correspondence vol. 11, enclosure to the letter to J. D. Hooker, 27 [November 1863], and this volume, letter from Asa Gray, 16 February 1864 and n. 3.
The reference is to the casualties incurred in the battles of the Wilderness and Spotsylvania in Virginia during the American Civil War. Between 5 and 12 May 1864 the Union forces reported 32,000 men killed, wounded, and missing, and the Confederate forces lost an estimated 18,000 men (see McPherson 1988, pp. 724–32).
CD enclosed a new photograph taken by his son William Erasmus Darwin (see letter from W. E. Darwin, [19 May 1864] and n. 8). The photograph is reproduced as the frontispiece to this volume.


‘Climbing plants’: On the movements and habits of climbing plants. By Charles Darwin. [Read 2 February 1865.] Journal of the Linnean Society (Botany) 9 (1867): 1–118.

Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.

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.

Howard, Richard A. 1988. Charles Wright in Cuba 1856–1867. Alexandria, Virginia: Chadwyck-Healey.

McPherson, James M. 1988. Battle cry of freedom: the Civil War era. New York and Oxford: Oxford University Press.

Mohl, Hugo von. 1863. Einige Beobachtungen über dimorphe Blüthen. Botanische Zeitung 21: 309–15, 321–8.

[Oliver, Daniel.] 1864a. Dimorphic flowers. Natural History Review n.s. 4: 243–8.

Orchids: On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing. By Charles Darwin. London: John Murray. 1862.

‘Three forms of Lythrum salicaria’: On the sexual relations of the three forms of Lythrum salicaria. By Charles Darwin. [Read 16 June 1864.] Journal of the Linnean Society (Botany) 8 (1865): 169–96. [Collected papers 2: 106–31.]

Willis, John Christopher. 1973. A dictionary of the flowering plants and ferns. 8th edition. Revised by H. K. Airy Shaw. Cambridge: Cambridge University Press.


Is slowly writing Lythrum paper [Collected papers 2: 106–31].

Thanks for [Charles?] Wright’s observations on orchids

– could he note what attracts insects to Begonia and Melastoma? H. Crüger, who was going to observe Melastomataceae, has died.

Describes the climbing habits of Bignonia capreolata and Eccremocarpus scaber.

How does AG know the perfect flowers of Voandzeia are quite sterile?

He has a case of dimorphism in holly; asks AG to report on American hollies.

Letter details

Letter no.
Charles Robert Darwin
Asa Gray
Sent from
Source of text
Gray Herbarium of Harvard University (79)
Physical description
ALS 6pp

Please cite as

Darwin Correspondence Project, “Letter no. 4511,” accessed on 19 April 2024,

Also published in The Correspondence of Charles Darwin, vol. 12