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Darwin Correspondence Project

From Fritz Müller   2 August 1866

Desterro, Brazil

August. 2. 66.

My Dear Sir,

Your kind letter of May 23d arrived here only July 24th.—1 In the meantime I could observe but a few specimens of one of our species of Oxalis; the length of the styli is very variable even in the flowers of the same plant, but whether the species is really trimorphic, I am not yet able to say.2

In my last letter I gave you a short account of an Orchid having three fertile stamens.3 The species is not very rare and I have already seen numerous ears, all the flowers of which showed the same number of fertile stamens. In a closely allied species from Bahia,4 which I saw in the garden of a Frenchman, I was much surprised at finding but one fertile stamen as in other plants of the tribe. It is curious, that the number of fertile stamens while it furnishes an excellent character for dividing the Orchids into two main groups, in this case is not even of generic value.5

Have you ever seen the flowers of Notylia?6 The stigma forms a very narrow slit, to which I found it impossible to cause the pollinia to adhere; at the same time the ovula have a very rudimentary appearance. Thus for some time I supposed the plant to be a male one, but afterwards I met with seed-capsules, the columna of which had evidently borne an anthera, while the stigma seemed to have been of the same form as in the supposed male flowers. Besides I convinced myself that in some other Orchids the ovula are in a very rudimentary estate at the time when the flower is expanded and that only some weeks afterwards they become ready for impregnation. This is, for instance, the case with two self-fertilizing species of the tribe of Epidendreae; (one of them belongs to the genus Isochilus).— Of these species I can send you some drawings if you shd desire it.—7

The fine Orchid, of which I send you a drawing, seemed to me to be interesting by the two stigmas being widely separated and situated at the inside of leaf-like processes projecting beyond the anther.—8

In your paper on the dimorphism of Linum you say that it had occurred to you, that possibly a species might be dimorphic in function, though not in structure.9 Some observations, which I casually made, seem to confirm this view and to prove that some species are completely barren or nearly so with pollen of the same individual plant. Thus I saw a large plant of an Octomeria; it had more than eighty monophyllous stalks,10 each with about a dozen yellow flowers; on most of the stigmas which I examined I found numerous (6–12) pollinia; but this plant yielded only two seed-capsules. Afterwards I have seen other plants, apparently of the same species, with numerous seed-capsules. I must add, that in the neighbourhood of the first plant I could not detect any other plant of the same species.— A very large plant of a Serjania, widely spreading over a hedge, and as far as I know, about a mile distant from the next plant of the same species, (the same, from which the fig. 20 of my paper on the wood of climbing plants11 was taken) was covered for many weeks by thousands of flowers, which were visited all the day long by numberless insects, (—humble-bees, beetles, butterflies, etc.—); but only very few seed-capsules were produced in the last weeks and I suppose, from their appearance, that none of these capsules, (as yet unripe), will give good seed.— Last year I had raised some plants of Eschscholtzia californica; one of them began to flower about a month before the others, and in this time it yielded not even a single seed-capsule; but no sooner had a neighbouring plant expanded its first flowers, than germens12 of the former plant began to swell; the second plant was fertile from the beginning.—

⁠⟨⁠one or more sheets missing⁠⟩⁠

Seeds use to fall to the ground, as soon as the seed-capsules open and in this case they are commonly dark-coloured;13 if on the contrary, they remain attached to the open valvæ,14 in all the cases, I know, either the seeds themselves, or the arillus, or the interior of the valvæ are brightly coloured so as to attract the attention,15 which may carry the seeds to distant places. Thus the large valvæ of a Tabernaemontana are filled with a bright red pulpa;—the black and shining seeds of a Paullinia are half-imbedded into a white arillus and fixed to red valvæ,—and the seeds of a fine small tree related to Acacia or Inga, which also for some time remain attached to the valvæ, are black and white and visible at a great distance.—

⁠⟨⁠half a page excised⁠⟩⁠ hundred miles beyond the actual sea-coast was once covered by a huge glacier!—?—16

I am very glad to hear that Nägeli and my old friend Oscar Schmidt are with us.—17 My brother, Dr. Hermann Müller of Lippstadt, (Prussia) who is thoroughly conversant with the natural history of mosses, is collecting the facts bearing on the change of species, which these plants may offer.—18

Wishing that this letter may find you in good health, believe me, dear Sir, with sincere respect very truly yours

[Enclosure 1]19


Columna of Notylia. a. from the side. b. front view. c. from the side after removing anther. d transversal section.—

[Enclosure 2]20

June. 5 66.


F.M. pinx.21

CD annotations

1.1 Your kind … desire it.— 3.11] crossed ink
4.1 The fine … the same species. 5.10] ‘Dichogamy Fr. Muller Aug 22—1866—’ added in margin blue crayon
5.1 In your … beginning.— 5.21] scored ink
5.5 Octomeria] ‘Malaxideæ?’ added above ink22
5.17 Last year … beginning.— 5.21] scored red crayon; ‘Escholtzia’ added red crayon; ‘Dichogamy Fritz Muller Aug 2. 1866—’ added ink
6.1 Seeds … distance.— 6.9] enclosed in square brackets, blue crayon
7.1 hundred … yours— 9.2] crossed ink
Enclosure 1: ‘stigma so narrow a slit that pollinia cannot be inserted (Probably long [interl] pedicel in)’ ink23 CD note: Beauty of seeds or of inside of pods for dissemination: F. Muller. Aug. 1866 | In Portfolio for addition to Dom. Animals, a letter with coloured drawings of other seeds.24


In his letter of 23 May 1866, CD had mentioned Friedrich Hildebrand’s recent work on trimorphic species of Oxalis and asked Müller to investigate whether there were different forms in species of Oxalis in his area. CD put the specimens that Müller enclosed in an envelope labelled ‘Oxalis Brazil variable   F. Muller Aug 2d/66/’. The specimens are in DAR 142: 97.
Müller refers to his letter of 1 June 1866, which has not been found (see letter to Fritz Müller, 23 August [1866]). He did, however, give an account of the orchid with three fertile anthers in letters to Max Johann Sigismund Schultze (2 June 1866) and Hermann Müller (1 July 1866; the letters are reproduced in Möller ed. 1915–21, 2: 83–4, 86–9). Müller described the orchid as a species of the orchid tribe Epidendreae with three fertile anthers, two in the outer whorl and one in the inner whorl (see Möller ed. 1915–21, 2: 87–8).
Bahia is a state (formerly a province) in north-eastern Brazil. CD described the area in his Journal of researches, pp. 589–91.
The ‘two main groups’ that Müller refers to are the Cypripedioideae (lady’s slipper orchids), which have two fertile anthers, and most other orchids, which have one. Müller later published his observations on the species of Epidendrum with three fertile anthers (see F. Müller 1868a, 1869, and 1870) and CD added a reference to Müller’s work in Orchids 2d ed., p. 148.
See first enclosure. Müller sent CD specimens of Notylia attached to the diagram. These are in DAR 142: 38.
In botanical nomenclature, a ‘tribe’ is a subdivision of a family, and contains a number of genera. Isochilus is one genus within the tribe Epidendreae. No drawings of Isochilus by Müller have been found in the Darwin Archive–CUL, but a diagram found in Müller’s papers, dated 24 July 1866, and identified as Isochilus, is reproduced in Möller ed. 1915–21, 2: 87.
Müller enclosed an unlabelled drawing of an orchid and a specimen of the flower with this letter. These are in DAR 76: B33a. See second enclosure and n. 21. The orchid in the drawing has been identified as Sophronitella violacea, a Brazilian member of the subtribe Laeliinae, which also includes Isochilus (identification made by Robert L. Dressler from a scan of Müller’s drawing; see also Dressler 1981, p. 226, and Dressler 1993, p. 275).
Müller refers to ‘Two forms in species of Linum, p. 82 (Collected papers 2: 104).
Monophyllous: ‘of a plant: having a single leaf or leaflet’ (OED).
The reference is to F. Müller 1866b, and figure 20 of the table that accompanied the article.
Germen: ‘an ovary’ (OED).
CD pasted this paragraph into his Experimental notebook and added some notes (DAR 157a: 81; the fragment has since been moved to DAR 157a: 102). See CD note transcribed below the letter.
Valve: ‘one of the halves or sections of a dehiscent pod, pericarp, or capsule’ (OED).
Müller presumably meant ‘to attract the attention of birds’. In another letter in which he discussed the function of brightly coloured seeds, Müller wrote that the mechanism was clearly designed to attract birds (see letter from Fritz Müller to Hermann Müller, 29 October 1866, reproduced in Möller ed. 1915–21, 2: 94–8; the reference is on p. 95).
The preceding part of this section of the letter has not been found. Müller may be referring to the hypothesis advanced by Louis Agassiz that the Amazon valley was once covered by a huge glacier (see letter from Asa Gray, 27 August 1866 and nn. 3 and 4). Müller had mentioned Agassiz’s research on the Amazon river in an earlier letter (see Correspondence vol. 13, letter from Fritz Müller, 5 November 1865).
Müller refers to Carl Wilhelm von Nägeli and Oskar Schmidt (see letter to Fritz Müller, 23 May 1866 and n. 16). Schmidt had been a friend of Müller’s ever since they were students at Greifswald (Möller ed. 1915–21, 3: 25).
Hermann Müller later published a group of articles on mosses in Verhandlungen des botanischen Vereins der Provinz Brandenburg vol. 8; one of these presented evidence from mosses that supported Darwinian transmutation theory (H. Müller 1866). CD’s annotated copy is in the Darwin Pamphlet collection–CUL.
Müller affixed a specimen of Notylia to the diagram. CD put the diagram and specimen into an envelope labelled, ‘Orchids. F. Muller Aug 2. 1866’. See n. 6, above.
See n. 8, above.
F.M. pinxit: ‘F. M. drew [it]’ (Latin).
The genus Octomeria was included in the orchid tribe Malaxideae (Malaxeae) by John Lindley (see Lindley 1853, p. 181). It is now generally put in the tribe Epidendreae (see Mabberley 1997).
CD described the pedicel of the pollinium in Orchids, pp. 6–7. In modern orchid terminology, the pedicel of the pollinium is called the stipe (Dressler 1981, p. 315).
CD refers to a portfolio of notes and material for Variation. He kept a number of such portfolios, amassed over a long period of time and since dispersed. The likely contents of some portfolios were reconstructed when some of CD’s papers were catalogued in 1932 (see DAR 220: 13). One portfolio is described as follows: ‘Scraps and notes on variation’.


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–.

Dressler, Robert L. 1981. The orchids: natural history and classification. Cambridge, Mass., and London: Harvard University Press.

Dressler, Robert L. 1993. Phylogeny and classification of the orchid family. Cambridge: Cambridge University Press.

Journal of researches: Journal of researches into the geology and natural history of the various countries visited by HMS Beagle, under the command of Captain FitzRoy, RN, from 1832 to 1836. By Charles Darwin. London: Henry Colburn. 1839.

Lindley, John. 1853. The vegetable kingdom; or, the structure, classification, and uses of plants, illustrated upon the natural system. 3d edition with corrections and additional genera. London: Bradbury & Evans.

Mabberley, David J. 1997. The plant-book. A portable dictionary of the vascular plants. 2d edition. Cambridge: Cambridge University Press.

OED: The Oxford English dictionary. Being a corrected re-issue with an introduction, supplement and bibliography of a new English dictionary. Edited by James A. H. Murray, et al. 12 vols. and supplement. Oxford: Clarendon Press. 1970. A supplement to the Oxford English dictionary. 4 vols. Edited by R. W. Burchfield. Oxford: Clarendon Press. 1972–86. The Oxford English dictionary. 2d edition. 20 vols. Prepared by J. A. Simpson and E. S. C. Weiner. Oxford: Clarendon Press. 1989. Oxford English dictionary additional series. 3 vols. Edited by John Simpson et al. Oxford: Clarendon Press. 1993–7.

Orchids 2d ed.: The various contrivances by which orchids are fertilised by insects. By Charles Darwin. 2d edition, revised. London: John Murray. 1877.

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.

‘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.]


Gives some observations on orchids and on some plants which seem to be dichogamous.

Letter details

Letter no.
Johann Friedrich Theodor (Fritz) Müller
Charles Robert Darwin
Sent from
Source of text
DAR 76: B33, 33a; DAR 157a: 81, 102; DAR 142: 38
Physical description
AL inc †, 2 sketches †

Please cite as

Darwin Correspondence Project, “Letter no. 5173,” accessed on 19 May 2024,

Also published in The Correspondence of Charles Darwin, vol. 14