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Darwin Correspondence Project

From Fritz Müller   18 October 1869

Itajahy, Sa. Catharina, Brazil,

Octr. 18. 1869.

My dear Sir

I received some weeks ago your kind letter of July 18th and am very sorry to learn from it, that you have been more unwell than usual.1 But I hope, that in the meantime you will have recovered again your health, so precious to your numerous friends and admirers.

I have been trying lately a new series of experiments on our self-impotent Abutilon.2 During the winter (from April to August) all my plants, though continuing to flower, had become quite sterile even with pollen from distinct plants. In the meantime one of the two plants, which I supposed to be mutually sterile, had been destroyed by an inundation of the Itajahy, so that I have been prevented from trying by more experiments the exactness of this supposition.— All my plants are descending from seeds of the same pod. Now among them is one, which is distinguished by pale flowers, by longer styli exserted before the expanding of the corolla and by much smaller stigmas. The pollen of this plant fertilizes the flowers of the others; but it has hitherto not yet yielded a single ripe pod. When fertilized with own pollen, the whole flowers fall off, as do those of the other plants, whilst when fertilized with pollen of a distinct plant, only the corolla falls off and the germen begins to swell a little; but in from 5 to 15 days the young pods are dropped. (they wd require about 30 days to ripen.) The same plant differs also from the rest, when fertilized with pollen of two distinct species of Abutilon (a cultivated one, (A. b. striatum?) and an endemic one);3 in this case the whole flowers fall off a few days after fertilization, while the other plants, when thus fertilized, yield fine pods with numerous seeds, more numerous indeed than in most pods naturally fertilized by insects. For instance 8 pods fertilized by insects contained from 11 to 52 (on an average 35,4) seeds; 7 artificially fertilized pods contained from 43 to 68 (on an average 55,7) seeds; and 3 pods fertilized with pollen of Abutilon stiatum (?) contained 46, 49 and 62 seeds (on an average 52,3)— Thus, as in many Orchids, self-impotence in our Abutilon appears to be accompanied by a great facility of being fertilized by pollen of distinct species.—4

Of the Eschscholtzia, raised last year from your seed, a single plant has survived; it is now flowering profusely since the beginning of Septbr., but shows only a few very poor pods, of which probably none will produce good seeds.5 In february or March I had sown some of the Eschscholtzia seeds, which you have sent me this year, but in consequence of the unfavourable weather, they did not germinate, the rest, sown in July, are growing well, but as yet far from flowering.—6 I hear from Prof. Hildebrand that in Hypecoum littorale, as in Eschscholtzia, only crossed flowers are producing well developed seed-capsules.7

I think, I told you already, that all the seedlings from a longstyled white Oxalis (O. Martiana Zucc., as I hear from Kew) legitimately fertilized with pollen of the long stamens of a midstyled plant are either longstyled or midstyled, without a single short-styled plant. Of 15 plants, which are now flowering, 10 are longstyled and 5 midstyled.—8

Of the monstrous Begonia mentioned in a former letter, I raised numerous seedlings; some are now beginning to expand their first flowers, but only one of these has inherited the monstrosity of the parent-plant, the rest bearing normal male flowers.—9

In one of your letters you called my attention on perennial Passiflora.10 I have in consequence planted several species into my garden; only 2 have as yet flowered, & these are self-sterile. In one species the first flowers, which appeared after transplantion, had contabescent anthers.

As to the fertilization of Passiflora, Delpino thinks in his interesting “Ulteriori osservazioni sulla Dicogamia”, which I recd a few days ago) that in the larger species this is effected by humming birds.11 I had come to the same conclusion by observing how frequently these flowers are visited by humming-birds, while I did not yet see neither humble-bees, nor butterflies, nor any other large insects able to fertilize them.

CD annotations

1.1 I … admirers. 1.4] ‘[Abution]blue crayon
2.1 I … plants. 2.3] crossed blue crayon
2.3 In … insects. 2.18] scored blue crayon
3.1 Of … year, 3.4] scored red crayon
4.1 I think, … flowers.— 5.3] crossed blue crayon
Top of letter: ‘F. Muller | Hybridism in [illeg]ink


Müller refers to Abutilon striatum (redvein Indian mallow). The endemic species was later named A. darwinii (see Cross and self fertilisation, pp. 333–4).
For Müller’s earlier work on self-sterility and crossing in orchids, see Correspondence vol. 15, letter from Fritz Müller, 1 April 1868.
CD had sent seeds of Eschscholzia californica (California poppy) with his letters of 30 January [1868] and 3 April [1868]; Müller had obtained seven plants from these seeds (see Correspondence vol. 16, letter from Fritz Müller, 9 September 1868 and n. 11).
Müller may refer to seeds of Eschscholzia californica sent by CD with his letter of 3 April [1868] (Correspondence vol. 16). CD sent more seeds of E. californica shortly after his letter of 14 March 1869 (see letter from Fritz Müller, 15 June 1869).
Friedrich Hildebrand reported his observations on self-sterility in Hypecoum and Eschscholzia in his paper ‘Ueber die Bestäubungsvorrichtungen bei den Fumariaceen’ (On the contrivances for pollination in the Fumariaceae; Hildebrand 1870). In this paper H. procumbens and H. grandiflorum are the species discussed. No letter from Hildebrand on this subject before October 1869 has been found.
Oxalis martiana is now O. latifolia. This is probably the species that Müller first described to CD in 1867 (see Correspondence vol. 15, letter from Fritz Müller, 17 July 1867 and n. 4).
The last two paragraphs of the letter are reproduced from a copy that was enclosed with the letter to T. H. Farrer, [27 November 1869]. See Correspondence vol. 15, letter to Fritz Müller, 2 November 1867 and n. 13.


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.

Delpino, Federico. 1868–75. Ulteriori osservazioni sulla dicogamia nel regno vegetale. 2 parts. Milan: Giuseppe Bernardoni. [Originally published in Atti della Societa Italiana di Scienze Naturali Milano 11 (1868): 265–352; 12 (1869): 179–233; 13 (1870): 167–205; 17 (1874): 266–407.]


Describes experiments to test the fertility of Abutilon, which appears self-sterile,

and briefly mentions dichogamy in Eschscholzia.

Letter details

Letter no.
Johann Friedrich Theodor (Fritz) Müller
Charles Robert Darwin
Sent from
Santa Catharina, Brazil
Source of text
DAR 76: B178, Linnean Society of London (LS Ms 299/12)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 6943,” accessed on 15 May 2021,

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