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Darwin Correspondence Project

To J. E. Todd   10 April 1882

Down, | Beckenham, Kent. | (Railway Station | Orpington. S.E.R.)

April 10th 1882.—

Dear Sir

I hope that you will excuse the liberty which as a stranger I take in begging a favour of you. I have read with unusual interest your very interesting paper in the American Naturalist on the structure of the flowers of Solanum rostratum, & I shd. be grateful if you would send me some seeds in a small box (telling me whether the plant is an annual, so that I may know where to sow the seeds), in order that I may have the pleasure of seeing the flowers & experimentising on them.1 But if you intend to experimentise on them, of course you will not send me the seeds, as I shd. be very unwilling to interfere in any way with your work. I shd. also rather like to look at the flowers of Cassia chamæcrista.2

Many years ago I tried some experiments in a remotely analogous case & this year am trying others. I described what I was doing to Dr. Fritz Müller (Blumenau, Sta. Catharina, Brazil) & he has told me that he believes that in certain plants producing 2 sets of anthers of a different colour, that bees collect the pollen from one of the sets alone.3 He wd. therefore be much interested by your paper, if you have a spare copy that you could send him. I think, but my memory now often fails me, that he has published on the subject in Kosmos.4

Hoping that you will excuse me, I remain, Dear Sir | Yours faithfully | Ch. Darwin

P.S. In my little book on the Fertilisation of Orchids, you will find under Mormodes ignea, an account of a flower, laterally asymmetrical, & which I think that I called right-handed or left-handed flowers.—5


Todd’s paper on the flowers of Solanum rostratum (a member of the nightshade family) was published in the April issue of the American Naturalist (Todd 1882); there is a copy in the Darwin Pamphlet Collection–CUL.
Todd had also discussed the flowers of Cassia chamaecrista (a synonym of Chamaecrista fasciculata var. fasciculata, a leguminous plant) in Todd 1882. Their structure, like the flowers of Solanum rostratum, is asymmetric in order to facilitate cross-fertilisation.
Fritz Müller had described to CD the behaviour of pollen-eating bees visiting flowers of Lagerstroemia, the genus of crape myrtle. The bees were attracted to bright yellow pollen on short stamens, while ignoring the less noticeable green pollen on longer stamens. Müller hypothesised the one type of anthers served to attract insects, while the other ensured cross-fertilisation (Correspondence vol. 29, letter from Fritz Müller, 7 February 1881).
Müller had not, in fact, published on the topic in Kosmos, but Hermann Müller had communicated some of his brother’s observations in a letter published in Nature, 4 August 1881, pp. 307–8, and observations of his own in Nature, 9 November 1882, p. 30. Fritz Müller later mentioned having been in contact with Todd in another letter about the different types of stamens published in Nature, 15 February 1883, pp. 364–5. A paper written by Hermann Müller, summarising his own and Fritz Müller’s further observations, and including Todd’s work on Cassia chamaecrista, was later published in Kosmos (H. Müller 1883b).
See Orchids, pp. 249–51; CD noted that its front surface, ‘including the anther, rostellum, and the upper part of the stigma’, faced ‘laterally to either the right or left hand in the flowers on the opposite sides of the spike’ (ibid., p. 251).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Müller, Hermann. 1883c. Arbeitstheilung bei Staubgefässen von Pollenblumen. Kosmos 13: 241–59.

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.

Todd, James Edward. 1882. On the flowers of Solanum rostratum and Cassia chamæcrista. American Naturalist 16: 281–7.


Requests seeds of Solanum rostratum.

Fritz Müller believes that in plants with anthers of different colours, bees collect from one set alone.

Suggests JET send copy of paper ["Flowers of Solanum rostratum and Cassia chamaecrista", Am. Nat. 16 (1882): 281–7] to Müller.

Letter details

Letter no.
Charles Robert Darwin
James Edward Todd
Sent from
Source of text
Department of Special Collections, Kenneth Spencer Research Library, University of Kansas (KU MS C78)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 13766,” accessed on 4 June 2023,