To R. I. Lynch   23 August [1877]1

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R. [Abinger Hall, Surrey.]

Aug. 23d

Dear Sir

If you have Erythrina crista-galli2 in any of your greenhouses, will you kindly look & see whether it goes to sleep.— This is the case with E. caffra & coralliflora (which I had from Kew), as the 3 leaflets fall vertically down at night.3 On the other hand there is a plant of E. crista-galli at a house, where I am now staying, which is nailed against a wall out of doors & the leaves do not sleep, & this puzzles me.—4

I & my son Francis have been observing with great care your discovery of the very singular movements of the leaflets of Averrhoa, & the phenomenon is a very interesting one.—5 We have been able to record the exact angular amount of movement & time of movement. The case is equal to that of Hedysarum gyrans.—6 I do not believe I shd. have ever have noticed the movement had it not been for your information

Dear Sir | yours faithfully | Ch. Darwin

1
The year is established by the relationship between this letter and the letter from R. I. Lynch, [28 August 1877].
2
Erythrina crista-galli is the cockspur coral tree.
3
According to an entry in the Outwards book (Royal Botanic Gardens, Kew), CD had been sent ‘Erythrinas’ on 16 July 1877; the species sent were not named, but were evidently Erythrina caffra (coast coral tree) and E. corallifera (a synonym of E. corallodendron, coral erythrina). CD discussed movement in E. corallodendron in Movement in plants, pp. 367, 405.
4
In Movement in plants, p. 319, CD noted that Erythrina crista-galli required the proper temperature to sleep, and mentioned the fact that a specimen nailed against a wall did not sleep. CD stayed at Abinger Hall from 20 to 25 August 1877 (see ‘Journal’ (Appendix II)).
5
Lynch had observed spontaneous movement during the day in leaves of Averrhoa bilimbi (see first and second letters from R. I. Lynch, [before 28 July 1877]).
6
CD discussed Hedysarum gyrans in Movement in plants, but referred to it as Desmodium gyrans; both names are synonyms of Codariocalyx motorius (telegraph or semaphore plant). In ibid., p. 330, CD wrote that the spontaneous movement of leaflets of Averrhoa bilimbi rivalled those of D. gyrans.

Manuscript Alterations and Comments

2.1 & … Francis] interl

Please cite as “DCP-LETT-11110,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-11110