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Darwin Correspondence Project

From Fritz Müller1   19 October 1877

Blumenau, Sa. Catharina, Brazil

19. October 1877.

Verehrter Herr!

Obwohl ich Ihnen kaum etwas mitzutheilen habe, darf ich doch nicht länger mit dem Ausdruck meines herzlichen Dankes zögern für Ihr Buch über die verschiedenen Formen von Blüten, welches mir grosse Freude gemacht hat.2 Es war für mich sehr anregend, im Zusammenhang und mit so vielen werthvollen Zusätzen, all Ihre bewundernswerthen Beobachtungen und Versuche über verschiedengrifflige (heterostyle) Pflanzen zu verfolgen.

You mention (“Different Forms of Flowers,” page 331) the deficiency of glands on the calyx of the cleistogamic flowers of several Malpighiaceæ, suggesting, in accordance with Kerner’s views, that this deficiency may be accounted for by the cleistogamic flowers not requiring any protection from crawling insects.3 Now I have some doubt whether the glands of the calyx of the Malpighiaceæ serve at all as a protection. At least, in the one species, the fertilisation of which I have very often witnessed, they do not. This species, Bunchosia gaudichaudiana, is regularly visited by several bees belonging to the genera Tetrapedia and Epicharis. These bees sit down on the flowers gnawing the glands on the outside of the calyx, and in doing so the under side of their body is dusted with pollen, by which, afterwards, other flowers are fertilised.4

There are here some species of Solanum (for instance S. palinacanthum) bearing on the same plant long-styled and short-styled flowers. The short-styled have papillæ on the stigma and apparently normal ovules in the ovary, but notwithstanding they are male in function, for they are exclusively visited by pollen-gathering bees (Melipona, Euglossa, Augochlora, Megacilissa, Eophila, n. g., and others), and these would probably never insert their proboscis between the stamens.5

In a few months I hope to be able to send you seeds of our white-flowered violet with subterranean cleistogamic flowers. I was surprised at finding that on the Sèrra (about 1,100 metres above the sea) this violet produced abundant normal fruits as well as subterranean ones, while at the foot of the Sèrra, though it had flowered profusely, I could not find a single normal fruit, and subterranean ones were extremely scarce.6

According to Delpino the changing colours of certain flowers would serve to show to the visiting insects the proper moment for effecting the fertilisation of these flowers.7 We have here a Lantana, the flowers of which last three days, being yellow on the first, orange on the second, purple on the third day. This plant is visited by various butterflies. As far as I have seen the purple flowers are never touched. Some species inserted their proboscis both into yellow and into orange flowers (Danais erippus, Pieris aripa), others, as far as I have hitherto observed, exclusively into the yellow flowers of the first day (Heliconius apseudes, Colœnis julia, Eurema leuce).8 This is, I think, a rather interesting case. If the flowers fell off at the end of the first day the inflorescence would be much less conspicuous; if they did not change their colour much time would be lost by the butterflies inserting their proboscis in already fertilised flowers.

In another Lantana the flowers have the colour of lilac, the entrance of the tube is yellow surrounded by a white circle; these yellow and white markings disappear on the second day.9

Mr. Leggett’s statements about Pontederia cordata appear to me rather strange, and I fear that there is some mistake. In all the five species of the family which I know the flowers are so shortlived, lasting only one day, that a change in the length of the style is not very probable.10 In the long-styled form of our highland Pontederia the style has its full length long before the flowers open. In my garden this Pontedaria is visited by some species of Augochlora collecting the pollen of the longest and mid-length stamens; they are too large to enter the tube of the corolla, and have too short a proboscis to reach the honey; they can only fertilise the long-styled and mid-styled forms, but not the short-styled.11

Among the secondary sexual characters of insects the meaning of which is not understood, you mention (“Descent of Man,” vol. i., p. 345) the different neuration in the wings of the two sexes of some butterflies. In all the cases which I know this difference in neuration is connected with, and probably caused by, the development in the males of spots of peculiarly-formed scales, pencils, or other contrivances which exhale odours, agreeable no doubt to their females. This is the case in the genera Mechanitis, Dircenna, in some species of Thecla, &c.,12

Mit wiederholtem herzlichsten Dank bin ich, werther Herr, in aufrichtiger Hochachtung treulichst der Ihrige | Fritz Müller.

Footnotes

For a translation of the first part of this letter and the closing, see Appendix I. According to Alfred Möller, all Fritz Müller’s letters to CD were written in English (see Möller ed. 1915–21, 2: 72 n.); most of them have not been found. Many of the letters were later sent by Francis Darwin to Möller, who translated them into German for his Fritz Müller: Werke, Briefe und Leben (Möller ed. 1915–21). Möller also found final drafts of some Müller letters among the Fritz Müller papers and included these in their original English form (ibid. 2: 72 n). Where the original English versions are missing, the published version, usually appearing in German translation, has been used. In this case, the English part of the letter was transcribed from the copy that appeared in Nature, 29 November 1877, p. 78 (see letter to Nature, 21 November [1877]). In the German version of this letter, the order of some of the paragraphs is different (see Möller ed. 1915–21, 2: 363–4).
Müller’s name is on CD’s presentation list for Forms of flowers (see Appendix IV).
CD had cited Anton Kerner von Marilaun’s ‘Die Schutzmittel der Blüthen gegen unberufene Gäste’ (The protective measures of flowers against uninvited guests; Kerner von Marilaun 1876, p. 25); Kerner von Marilaun had maintained that fluid secreted by glands of the calyx generally served to protect flowers from crawling insects.
Bunchosia gaudichaudiana is a synonym of Hiraea gaudichaudiana. Tetrapedia and Epicharis are genera of oil-collecting solitary or semi-solitary bees. Müller had described these bees in his letter to CD of 20 April [1874] (Correspondence vol. 22).
Solanum palinacanthum is an andromonoecious species, that is, it bears flowers that are male (short-styled) and hermaphrodite (long-styled) on the same plant (Coleman and Coleman 1982). Melipona is a genus of stingless bees; most species collect both pollen and nectar at different times of day, but some species forage exclusively for pollen or nectar (Sommeijer et al. 1983). Euglossa is the genus of orchid bees; females of the genus collect pollen while males are oil-collecting. Augochlora is a genus of sweat bees. Megacilissa is a former genus whose members are now included in the three genera of the tribe Caupolicanini (Michener 2007). The genus name Eophila was never published as a bee genus; it is a genus of earthworms. Müller had earlier mentioned the name in a letter to Hermann Müller of 1 January 1874, noting that it was a type of mining bee (family Andrenidae; Möller ed. 1915–21, 2: 249). The andrenid bee Oxaea flavescens has been recorded visiting flowers of S. palinacanthum (Lopes de Carvalho et al. 2001, p. 39).
Between 25 October and 20 December 1876, Müller and his friend Emil Odebrecht had travelled in the highlands of Santa Catarina to the source of the Uruguay river in the Serra do Mar (Sea Ridge) mountain ranges (see Möller ed. 1915–21, 3: 107, and West 2003, pp. 191–3). A brief description of some botanical observations made on this trip was published in Flora, 21 May 1877, pp. 239–40; Müller mentioned finding the white violets in full bloom with both open and cleistogamic flowers (ibid., p. 240). The species he observed was probably Viola subdimidiata, a native of this region (for more on its floral biology, see Freitas and Sazima 2003).
Federico Delpino had discussed colour changes in flowers in an article on plants requiring animal agency for fertilisation (Delpino 1873, pp. 176–7), published in Atti della Societa Italiana di Scienze Natural and later reprinted as part of a collection on dichogamy with different pagination (Delpino 1868–75; CD’s annotated copy is in the Darwin Library–CUL).
Lantana is a genus of the family Verbenaceae; flowers are produced in umbels with the oldest flowers on the outer edges. The species Müller described was probably L. camara. Danais erippus is a synonym of Danaus erippus (southern monarch); Pieris aripa is a synonym of Leptophobia aripa (mountain white). Heliconius apseudes is a synonym of H. sara (Sara longwing); Colaenis julia is a synonym of Dryas iulia (Julia longwing); Eurema leuce is Hall’s sulphur butterfly.
The species Müller described was probably Lantana montevidensis.
William Henry Leggett had described Pontederia cordata (pickerel weed) as having variable style lengths depending on the degree of floral development (Leggett 1875; see letter from W. H. Leggett, 15 January 1877).
In a later paper, Müller described the highland species of Pontederia as originating in Curitibanos (Fritz Müller 1883, p. 297); later researchers speculated that the species may have been Pontederia rotundifolia (tropical pickerelweed; Hazen 1917, p. 461). Müller had sent specimens of all three forms of this species; CD described them and noted differences in their pollen in Forms of flowers, pp. 185–7.
Mechanitis is a genus of tigerwing butterflies; Dircenna is a genus of clearwing butterflies. Both are in the family Nymphalidae. Thecla is the genus of hairstreak butterflies in the family Lycaenidae.

Bibliography

Coleman, James R. and Coleman, Marina A. 1982. Reproductive biology of an andromonoecious Solanum (S. palinacanthum Dunal). Biotropica 14: 69–75.

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

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.]

Delpino, Federico. 1873. Ulteriori osservazioni e considerazioni sulla dicogamia nel regno vegetale. Articolo IV. Delle piante zoidiofile. Atti della Società Italiana di Scienze Natural 16: 151–349.

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

Hazen, Tracy Elliot. 1917. The trimorphism and insect visitors of Pontederia. Memoirs of the Torrey Botanical Club, Proceedings of the semi-centennial anniversary of the Torrey Botanical Club 17: 459–84.

Leggett, William Henry. 1875. Pontederia cordata, L. Bulletin of the Torrey Botanical Club 6 (1875–9): 62–3.

Michener, Charles Duncan. 2007. The bees of the world. 2d edition. Baltimore: Johns Hopkins University Press.

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

Translation

From Fritz Müller1   19 October 1877

Blumenau, Sa. Catharina, Brazil

19. October 1877.

Dear Sir!

Although I have hardly anything to tell you, I must not delay any longer in expressing my heartfelt thanks for your book on the different forms of flowers, which gave me great delight.2 It was very stimulating for me to follow all your remarkable observations and experiments on heterostyled plants in context and with so many valuable additions.

[. . .]

Repeating my hearty thanks, I am, dear Sir, with the deepest respect very faithfully yours | Fritz Müller.

Footnotes

The letter contains portions in English which are not included here. For the original German of the published source, and the English portions from a different published source, see p. QQQQ.
Müller’s name is on CD’s presentation list for Forms of flowers (see Appendix IV).

Bibliography

Coleman, James R. and Coleman, Marina A. 1982. Reproductive biology of an andromonoecious Solanum (S. palinacanthum Dunal). Biotropica 14: 69–75.

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

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.]

Delpino, Federico. 1873. Ulteriori osservazioni e considerazioni sulla dicogamia nel regno vegetale. Articolo IV. Delle piante zoidiofile. Atti della Società Italiana di Scienze Natural 16: 151–349.

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

Hazen, Tracy Elliot. 1917. The trimorphism and insect visitors of Pontederia. Memoirs of the Torrey Botanical Club, Proceedings of the semi-centennial anniversary of the Torrey Botanical Club 17: 459–84.

Leggett, William Henry. 1875. Pontederia cordata, L. Bulletin of the Torrey Botanical Club 6 (1875–9): 62–3.

Michener, Charles Duncan. 2007. The bees of the world. 2d edition. Baltimore: Johns Hopkins University Press.

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

Summary

Doubts that glands of calyx of cleistogamic Malpighiaceae serve as protection.

Some species of Solanum bear long- and short-styled flowers on same plant.

Changing colours of some flowers may show insects the proper moment for fertilisation.

Doubts that the style of Pontederia cordata changes length.

Sexual difference in wings of some butterflies due to development in male of scales that emit odours to excite female.

Letter details

Letter no.
DCP-LETT-11191
From
Johann Friedrich Theodor (Fritz) Müller
To
Charles Robert Darwin
Sent from
Santa Catharina, Brazil
Source of text
Möller ed. 1915–21, 2: 363–4; Nature, 29 November 1877, pp. 78–9

Please cite as

Darwin Correspondence Project, “Letter no. 11191,” accessed on 28 July 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-11191.xml

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