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Darwin Correspondence Project

To F. J. Cohn   5 June 1878

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

June 5. 1878.

My dear Sir

It was exceedingly kind of you to send me so interesting a letter. I will forward it to my son Francis, who has gone to Germany for 2 months, & he will particularly like to read your letter.1 I have been the more interested by your details, as I published (Gardener’s Chronicle Jan 5 1861 p. 4) a short note with a rude drawing of the Achenes of the Australian Pumilio argyrolepis, which are of a curious shape, like the foot of a man.2 If they fall laterally on a damp surface, the exuded mucilage in drying, draws them upright, so that they appear as if gummed with great care to the surface. I afterwards heard that Decaisne had published a paper on the subject in the Ann. des Sciences Nat; & after reading it, looked at the Achenes of Senecio & some other compositæ; but I did not make out the details which you so clearly describe & figure.3 I have placed some of the seeds from your packet, under the microscope, but have as yet failed to see the viscid threads. Possibly this particular lot of seed may not have been quite ripe; for I cannot understand why I now fail to see what I formerly saw.

Believe me. | With cordial thanks. | Yours sincerely. | Charles Darwin.


The letter from Cohn has not been found; CD forwarded it with the letter to Francis Darwin, 5 [June 1878]. Francis Darwin had gone to study in Julius Sachs’s laboratory in Würzburg, Germany; see letter to W. T. Thiselton-Dyer, 2 June 1878 and n. 5.
CD’s note on Pumilo argyrolepis (a synonym of Siloxerus multiflorus) appeared in Gardeners’ Chronicle, 5 January 1861, pp. 4–5; see Correspondence vol. 9, letter to Gardeners’ Chronicle, [before 5 January 1861].
Joseph Decaisne’s paper ‘Sur la structure des poils qui couvrent le péricarpe de certaines Composées’ (On the structure of the hairs covering the pericarp of some Compositae; Decaisne 1839) was published in Annales des sciences naturelles (botanique); see also Correspondence vol. 20, letter to Friedrich Hildebrand, 9 February 1872, in which CD recommended the examination of the ‘curious adhesive filaments of mucus emitted by the Achenia of many Compositae’ and wondered about their function. Senecio is a genus in the Compositae (or Asteraceae, the daisy family); it includes ragworts and groundsels.


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

Decaisne, Joseph. 1839. Sur la structure des poils qui couvrent le péricarpe de certaines Composées. Annales des sciences naturelles (botanique) 2d ser. 12: 251–4.


Comments on achenia of Pumilio argyrolepis.

Letter details

Letter no.
Charles Robert Darwin
Ferdinand Julius Cohn
Sent from
Source of text
DAR 249: 73
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 11542,” accessed on 9 May 2021,