skip to content

Darwin Correspondence Project

From Daniel Oliver   12 March 1877

Herbm. | Royal Gardens Kew

12 Mar. 1877.

Dear Mr Darwin

With regard to cleistogamic flowers of Oxalis: is it quite clear that those which you find in O. sensitiva are cleistogams in the same sense as the late flowers of O. acetosella & Violet?1

I shd. suspect that they are merely arrested or imperfectly developed normal flowers—as you may find in probably many many-flowered inflorescences not of Oxalis only. The species you name is a many-flowered one.2 Of course there may subsist some relationship between such so-called arrested or abortive flowers & true cleistogams—but a distinction between them generally speaking is clear. From my own limited experience amongst true cleistogams I shd certainly say they are not likely to lend themselves to di- or tri-morphic practices!

The style if present in normal flower is nearly always 0 in true cleistogs. & the stamens anything from 1 anther to nine: Corolla 0 or 1–2 or nine little petals.

However—I fear the Herbm.—any help we can get out of it would be most unsatisfactory.

It is so rarely, to begin with, that specimens are selected with reference to 2–3-morphism. The only specimens that I remember collected to illustrate this matter are some sent by M. Gibert from the Monte Video Country & these are mostly if not all 1-flowd. species like O. Acetosella.3 I think it wd. be very desirable to apply to him specially for flowers in fluid.— I think it possible we may have some in fluid from him at the Museum. I will have enquiry made & let you know if we have.—

Very Sincerely yrs | D. Oliver


For CD’s letter asking about Oxalis, see Correspondence vol. 30, Supplement, letter to Daniel Oliver, 10 March 1877. CD described the cleistogamic flowers (permanently closed flowers adapted for self-fertilisation) of Oxalis sensitiva (a synonym of Biophytum sensitivum) and O. acetosella (wood sorrel) in Forms of flowers, pp. 321–4. CD had previously corresponded with Oliver about Oxalis acetosella in 1862 and 1863; see Correspondence vol. 10, letter to Daniel Oliver, 20 [April 1862], and Correspondence vol. 11, letter from Daniel Oliver, 27 November 1863 and n. 6. CD discussed Biophytum sensitivum in Cross and self fertilisation, p. 377, as an example of a species in the process of developing cleistogamic flowers. He was aware of the synonymy since he referred to it as Oxalis (Biophytum) sensitiva in Forms of flowers, p. 322, and he also recognised that its cleistogamic flowers were structurally similar to open flowers as well as being heterostyled. For CD’s conclusions about cleistogamy in the common violet (Viola odorata), see Forms of flowers, pp. 317–18.
The species mentioned has not been identified. CD discussed several species of Oxalis in Forms of flowers; for a list see ibid., p. 350. George Henry Kendrick Thwaites had sent CD flowers of Oxalis sensitiva from Ceylon (now Sri Lanka). See Correspondence vol. 30, letter to Daniel Oliver, 10 March 1877, and Correspondence vol. 25, letter to G. H. K. Thwaites, 26 March 1877.
Joseph Ernest Gibert sent plants to Kew from Montevideo, Uruguay (letter from Gibert to Joseph Dalton Hooker, 15 March 1872, JSTOR Global Plants,, accessed 24 November 2015).


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

Cross and self fertilisation: The effects of cross and self fertilisation in the vegetable kingdom. By Charles Darwin. London: John Murray. 1876.

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


Discusses the cleistogamous flowers of Oxalis. Thinks they may not be truly cleistogamous but merely arrested or imperfectly developed normal flowers.

Letter details

Letter no.
Daniel Oliver
Charles Robert Darwin
Sent from
Source of text
DAR 173: 35
Physical description
ALS 5pp

Please cite as

Darwin Correspondence Project, “Letter no. 10890,” accessed on 25 July 2024,