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Darwin Correspondence Project

From W. T. Thiselton-Dyer   [before 3 February 1878]1

I shall not seem presumptuous if I venture on a few more remarks.2 When seedvessels are freely exposed to the sun and air they tend to dry up prematurely and the seeds consequently would be apt to be small and so the progeny would stand a chance of being weakly.

If, however, the plant could ⁠⟨⁠draw its see⁠⟩⁠d vessels in⁠⟨⁠to shade⁠⟩⁠ ⁠⟨⁠2 or 3 words⁠⟩⁠ moisture the pod and, what is of more importance, its enclosed seeds would go on swelling much longer than they otherwise would do. In Mr Bentham’s Helianthemums the trick is just being learnt and Mr Bentham tells me this morning that it is his impression that some arrangement of the kind is far from uncommon ⁠⟨⁠in s⁠⟩⁠mall herb⁠⟨⁠aceous plants.⁠⟩⁠3

As a slight illustration I may mention that having put the pods of Amphicarpæa which you gave me in their envelope in my pocket—the warmth of my body caused the desiccation and consequent dehiscence of the aerial pods while the subterranean one was unaffected. The amphicarpic species of Lathyrus—which are all perhaps local races of L. sativus are dry country plants Syria, S. France, Portugal.4 In these the subterranean ⁠⟨⁠pods are⁠⟩⁠ produced from subterranean shoots with cleistogamic flowers which is a most singular arrangement but is an acquired habit as it does not occur in normal L. sativus

However, I am afraid I am guilty of presumption, for all this could not fail to occur to you.

Sir Joseph Hooker suggests Ceratopteris for Saporta’s fossil. This seems a very probable hypothesis   The obvious objection is that Ceratopteris having pinnate fronds is not ⁠⟨⁠di⁠⟩⁠chotomous5   ⁠⟨⁠But the⁠⟩⁠

CD annotations

1.1 When … prematurely 1.2] scored red crayon
3.1 having] del red crayon; ‘having’ red crayon
5.1 Sir … ⁠⟨⁠But the⁠⟩⁠ 5.3] crossed ink
Beginning of scrap: ‘(with regard to Amphicarpic habits,’ ink, square bracket in ms; ‘Keep’ ink del ink; ‘Dyer | (2)’ ink; ‘Keep’ ink circled ink


The date is established by the relationship between this letter and the letter to W. T. Thiselton-Dyer, 3 February [1878].
CD and Thiselton-Dyer had been discussing the function of plants burying seed capsules; see letter to W. T. Thiselton-Dyer, 31 January [1878].
In his letter of 29 January 1878, Thiselton-Dyer had referred CD to George Bentham’s description of Helianthemum procumbens (a synonym of Fumana procumbens; sprawling needle sunrose); Bentham thought that the branches being stretched along the ground prevented the seeds from drying out quickly (Bentham 1826, p. 85).
Amphicarpaea (hog peanut) is a small genus of vines in the legume family, Fabaceae. Thiselton-Dyer had visited Down from 26 to 28 January (Emma Darwin’s diary (DAR 242)). He had included a note on Lathyrus setifolius (brown vetchling), which bears both aerial and subterranean flowers and seeds, with his letter of 29 January 1878. Lathyrus sativus is the white pea.
In his letter to Gaston de Saporta of 31 January 1878, CD said that he had asked for Joseph Dalton Hooker’s identification of the tracing of a Permian leaf sent to him by Gaston de Saporta with Saporta’s letter of 16 December 1877 (Correspondence vol. 25); Saporta initially suggested the leaf might be related to Gingko. For drawings of the leaf, see Saporta and Marion 1885, 1: 231. Saporta named the species Dichoneuron hookeri. Thiselton-Dyer’s proviso about it not being dichotomous probably refers to the dichotomous venation, typical of Gingko leaves, as opposed to the reticulate venation in Ceratopteris.


Bentham, George. 1826. Catalogue des plantes indigènés des Pyrènées et du Bas-Languedoc, avec des notes et observations sur les espèces nouvelles ou peu connues; précédé d’une notice sur un voyage botanique, fait dans les Pyrénées. Paris: Madame Huzard imprimeur-libraire.

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


The amphicarpic habit.

Letter details

Letter no.
William Turner Thiselton-Dyer
Charles Robert Darwin
Sent from
Source of text
DAR 178: 91
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 5825,” accessed on 6 December 2021,