skip to content

Darwin Correspondence Project

From Fritz Müller   18 December 1869

Itajahy, Sa Catharina, Brazil

Decbr. 18. 1869

My dear Sir

I have to thank you for having kindly favoured me with a copy of your “Notes on the fertilization of Orchids” which contain a large number of interesting facts quite new to me.1

A few days ago I returned from an excursion, on which I made a rich harvest of dimorphic and trimorphic plants. There were about half a dozen dimorphic Rubiaceæ, and among them the beautiful Rudgea eriantha. 2


But the most interesting plant was a Pontederia, which I had long ago suspected to be trimorphic and which now indeed I found to be so.3

equivalent of 5 or 6 lines excised

This is, I think, the first case of trimorphism or dimorphism among monocotyledons and in irregular flowers. The three longer stamens do not alternate with the shorter ones, nor belong to the same whorl; one of the longer stamens is inserted to the anterior sepal, two to the lateral petals; one of the shorter ones to the posterior petal, which is marked with a yellow spot, and two to the lateral sepals. (In the allied monomorphic genus Heteranthera, at least in H. reniformis, the three shorter stamens of Pontederia are wanting.)4 I was much surprised, that among hundreds of plants I could not find a single mid-styled one, and I have have hardly any doubt, that this form does not exist in the Itajahy-mirim,5 where this species grows abundantly.— The long-styled and short-styled plants could be distinguished even from a distance, the flowers of the former being paler, than those of the latter; in the dried flowers this difference has disappeared.— In a former letter I have sent you a mid-styled flower of a second species of Pontederia, which has been introduced here some years ago from Rio de Janeiro.—6

As to dimorphic Rubiaceæ, Professor Hildebrand told me, that Bernouilli (in Guatemala) had observed Coffea arabica to be dimorphic, producing hermaphrodite and small female flowers; but this is an error.7 The small flowers are rudimentary and sterile ones which occasionally appear among the normal flowers. I have lately seen these aborted flowers in unusual number on coffee-trees, which had been damaged by hail some weeks before.

Of the Begonia with monstrous male flowers I have raised four lots of seedlings and it is curious, in how odd a manner the monstrosity has been transmitted.8 The female flowers, from which the seeds were obtained, had all been fertilized with pollen of monstrous male flowers.

〈    〉 seeds of a normal female flower. 〈    〉 〈o〉f which have normal and 2 monstrous 〈    〉 of 〈    〉 male 〈    〉

3d lot. Seeds of a female flower, which had 6 petals instead of 5.— 20 plants; 17 have flowered, all having normal male flowers.

4th lot. Seeds of two female flowers of a second plant, which also had 6 petals.—22 plants, of which 7 are flowering, only one of them producing monstrous male flowers.— Some of the 9 plants of the second lot, which had monstrous male flowers, showed this monstrosity only for a short time; the first male flowers were monstrous, but afterwards they produced and are now producing normal male flowers. Gærtner has already observed, that the first flowers (“Erstlingsblumen”) are often distinguished from the later ones by a greater number of stamens or pistils, by greater fertility etc. and I have myself lately observed some curious instances of this.9 In a plant of Eschscholtzia the first six or eight flowers had from 5 to 7 petals; afterwards not a single flower with more than 4 petals has appeared on this plant.

On a plant of Siphocampylus the first flowers of several branches had six petals instead of 5; the first of all flowers which this plant produced, had even 7 petals. A few sixpetaled flowers have also appeared among the other flowers of this plant; but these 6 petaled flowers are at least 100 times more numerous among the first flowers of the branches, than among the rest.—

On an umbel of Agapanthus the first flower had 5 segments instead of six.— On a Jussieua,10 which is extremely common on the banks of the Itajahy, and the flowers of which have normally 4 petals, the first flowers of the branches have not unfrequently 5 petals, and in this case there are generally also 5 sepals, 10 stamens and a 5 locular germen; but in one single flower there were 6 sepals, 5 petals, 10 stamens and a 4 locular germen.—

—To the list of self-impotent plants I may now add Tabernæmontana echinata, on which I lately tried some experiments. A Calonyction with very large white flowers appears to be self-impotent also;11 at least a plant in my garden is quite sterile with its own pollen; but I have no second plant and am therefore unable to say, whether it would be fertile with pollen of a distinct plant.—

A very strange case of graft-hybrids is recorded in one of the last numbers of the “Auxiliador da Industria nacional” (April 1869 pg 158). A “fazendeiro” of the province of Rio de Janeiro, Señr J. F. Silveira da Motta, says that he has obtained a green and red striped variety of sugar-cane by planting close together plants of the green and of the red sugar-cane; as well as yellow and red striped sugar-cane by planting in the same hole cuttings of yellow and of red sugar-cane.12 I confess that I have some doubts, whether these statements may be trusted; but I hope that I shall soon be able to repeat the experiments of Señr Silveira da Motta.

Permit me to repeat my thanks for all your kindness and believe me, dear Sir, with profound respect

very truly yours | Fritz Müller.

CD annotations

2.2 There were … eriantha. 2.3] scored red crayon
10.6 Gærtner … this. 10.8] double scored blue crayon
10.8 In a … germen.— 12.6] scored blue crayon
14.1 A very … sugar-cane. 14.6] crossed blue crayon
Top of letter: ‘Law of Variation Keep’ blue crayon
End of letter: ‘J Jenner Weirs case’13 pencil; ‘In a second letter he mentions case of a Cassia,— in which the first flowers on several racemes produced 2 carpels.— Hooker, mentions genus in which 2–5 carpels are normally produced.—’14 ink


A specimen of Rudgea eriantha (now R. coriacea), long-styled, is stuck to the letter at this point.
Specimens of Pontederia species were evidently attached to an excised portion of the letter beneath the Rudgea specimen. There is an empty envelope in DAR 109: B124 on which CD had written, ‘Pontederia from F. Müller introduced from Rio Janeiro & new seeds. suppose trimorphic   Measure Pollen—’. On Müller’s earlier observations of Pontederia, see Correspondence vol. 16, letter to Fritz Müller, 3 April [1868] and n. 5. Müller published a description of three forms of Pontederia in F. Müller 1871. CD described heterostyly in Pontederia (now Eichhornia, the water hyacinth), including Müller’s specimens, in Forms of flowers, pp. 183–7.
Heteranthera (mudplantains) and Pontederia (now Eichhornia) are genera in family Pontederiaceae. Heteranthera reniformis is the kidneyleaf mudplantain.
The reference is to a tributary of the Itajahy river (see West 2003, map, p. 70); the main river is now called Itajaí Açu.
Müller may have sent a specimen of Pontederia aquatica (now Eichhornia azurea) with a now incomplete letter in which he evidently discussed the plant; see Correspondence vol. 14, letter from Fritz Müller, [2 November 1866] and n. 16.
The references are to Friedrich Hildebrand and to Carl Gustav Bernoulli, a German coffee planter in Guatemala. Müller and CD had been discussing dimorphic flowers in the family Rubiaceae since 1866; see especially Correspondence vol. 16, letter from Fritz Müller, 31 October 1868.
For examples of Karl Friedrich von Gärtner’s observations of differences in early flowers, see Gärtner 1844, pp. 68, 100, and 220. There is a heavily annotated copy of Gärtner 1844 in the Darwin Library–CUL (Marginalia 1: 248–98).
Jussieua was a common misspelling of Jussiaea, a synonym of Ludwigia.
Müller and CD had been exchanging information on self-sterile plants since 1866 (see Correspondence vols. 14–16). CD included Müller’s reference to Tabernaemontana echinata and the Calonyction in his notes (DAR 76: 154b), and referred to the self-sterility of the former as observed by Müller in Cross and self fertilisation, p. 331. The name Tabernaemontana echinata has since been rejected (see Taxon 50 (2001): 1180); Müller probably referred to what is now called T. siphilitica. Calonyction is a synonym for Ipomoea.
The article by Ignácio Francisco Silveira da Mota was published in the Brazilian journal O Auxiliador da Industria Nacional. Fazendeiro: plantation-owner, rancher (Portuguese). For CD’s interest in graft-hybrids, see Variation 1: 390–7.
See letter to Fritz Müller, 12 May 1870 (Correspondence vol. 18). John Jenner Weir reported to CD the case of a horse born to a mare that had previously had a foal by a quagga; the horse had quagga-like characteristics (ibid., letter from J. J. Weir, 17 March 1870). In his reply to Weir, CD quoted a similar case reported to him by Müller in a letter that has not been found (ibid., letter to J. J. Weir, 17 March [1870]).
Müller mentioned Cassia in his letter of 29 March 1870 (Correspondence vol. 18). CD also refers to Joseph Dalton Hooker.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Cross and self fertilisation: The effects of cross and self fertilisation in the vegetable kingdom. By Charles Darwin. London: John Murray. 1876.

‘Fertilization of orchids’: Notes on the fertilization of orchids. By Charles Darwin. Annals and Magazine of Natural History 4th ser. 4 (1869): 141–59. [Collected papers 2: 138–56.]

Forms of flowers: The different forms of flowers on plants of the same species. By Charles Darwin. London: John Murray. 1877.

Gärtner, Karl Friedrich von. 1844. Versuche und Beobachtungen über die Befruchtungsorgane der vollkommeneren Gewächse und über die natürliche und künstliche Befruchtung durch den eigenen Pollen. Pt 1 of Beiträge zur Kenntniss der Befruchtung der vollkommeneren Gewächse. Stuttgart: E. Schweizerbart.

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.

Müller, Fritz. 1871. Ueber den Trimorphismus der Pontederien. Jenaische Zeitschrift für Medicin und Naturwissenschaft 6: 74–8.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.

West, David A. 2003. Fritz Müller. A naturalist in Brazil. Blacksburg, Va.: Pocahontas Press.


Discusses dimorphic and trimorphic plants; mentions especially Rubiaceae and a dimorphic monocotyledon.

Notes observations on the monstrous male flowers of Begonia,

and on self-sterile plants.

Letter details

Letter no.
Johann Friedrich Theodor (Fritz) Müller
Charles Robert Darwin
Sent from
Santa Catharina, Brazil
Source of text
DAR 109: B125–6
Physical description
4pp inc ††, CD note

Please cite as

Darwin Correspondence Project, “Letter no. 7029,” accessed on 18 June 2021,

Also published in The Correspondence of Charles Darwin, vol. 17