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Darwin Correspondence Project

From George Bentham   10 July 1877

25, Wilton Place. | S. W.

July 10/77

My dear Mr Darwin

I cannot help troubling you with a few lines to offer you my most cordial thanks for the fresh valuable contribution to the physiology of plant life contained in your ‘Different forms of Flowers’ just received1   In glancing through it my attention was specially called to the Chapter on Cleistogamic flowers which have always been to me a most interesting subject since I first observed them now more than fifty years ago—especially in Ononis minutissima as I noted in my Catalogue des plantes des Pyreneès (1826)2 and in Viola as I ascertained immediately 〈4 or 5 words missing〉 investigating 〈2 or 3 words missing

3 or 4 words missing〉 some slight alterations to make in your list of genera p. 312— Chapmannia and Stylosanthes to be omitted and Trifolium to be reinserted3   I mention this because I believe I was responsible for the supposed apetalous flowers of Arachis Stylosanthes and Chapmannia an account of which I published in the Linnean Transactions vol. XVIII. My error was pointed out by a Mr Neisler and I duly acknowledged it in Hooker’s Kew Journal vol VIII. p. 380.4 The fact is that the three genera Arachis Stylosanthes and Chapmannia are precisely similar in the exceptional structure of their flowers. The petals and stamens are fixed at the top of the slender calyx-tube   the long style enclosed in the tube is before fecundation continuous with the erect point of t〈 〉 [5 or 6 words obscured] 〈fecun〉dation the [5 or 6 words obscured] falls off with [4 or 5 words obscured] the ovary bends to a [3 or 4 words obscured] ovary is still so slender that I thought it was still unimpregnated and mistook the scar of the style for the stigmatic surface. When once I had discovered my error I carefully searched living and dried specimens of Stylosanthes and could discover no really cleistantherous or apetalous flowers.

They exist however in trifolium— not indeed in trif. subterraneum or other South European species which bury their pods but in the South American T. polymorphum Poir. Mart. Fl Bras. Legum— p. 36. In which the clusters of flowers at the base of the stems are I believe all Cleistogamous after the fashion of Lespedeza.5

I observe p. 79 you say that “hybrids of the first generation if raised from uncultivated plants are generally uniform in character”. Is that really the case? I observed natural hy〈b〉rids a good deal in the Pyrenees an〈d〉 〈  〉 of France especially i〈n〉 [large] [3 or 4 words illeg] Cistus Helianthemum Lin〈n〉 [3 words illeg] alluded to in my 〈2 or 3 words missing〉 Catalogue6 I concluded that certain individuals were hybrids 1. because they only occurred where the two parents grew in proximity 2 because the individuals were very few where the parents were in great numbers 3 because they set no seed however abundantly they flowered and 4 because few as they were no two were alike— And since that time all my observations on wild plants have tended to confirm these data especially as to species habitually propagated by seed. Where individuals are perpetuated by suckers or other bud-separation the conditions may be a little altered.

Pray excuse these observations   I am anxious to be corrected if I am wrong

Yours very sincerely | George Bentham

For various reasons I think that wild hybrids are generally if not universally of the first generation

CD annotations

1.6 Catalogue … Pyreneès 1.7] underl red crayon
1.7 (1826)] double underl red crayon


Bentham’s name appears on CD’s presentation list for Forms of flowers (see Appendix IV).
In Bentham 1826, p. 108, Bentham noted that flowers of Ononis minutissima growing in the lower Languedoc always lacked corollas in the spring.
In his Handbook of the British flora (Bentham 1858, p. 109), Bentham wrote of Viola: ‘In all the British species, except the Pansy, perfect flowers seldom set their fruits. The capsules and seeds are generally produced by minute flowers, almost without petals or stamens, which appear later in the year.’ In Forms of flowers, pp. 312–13, CD listed genera that included cleistogamic species. Trifolium is the genus of clovers. Stylosanthes is the genus of pencilflowers.
Arachis is the genus of peanuts. For Bentham’s statement about the existence of apetalous flowers in Arachis and Chapmannia, see Bentham 1838, pp. 156, 161. He retracted the claim, in particular as it regarded Stylosanthes, in Hooker’s Journal of Botany and Kew Garden Miscellany 8 (1856): 380 (see also ibid. 7 (1855): 177–9). For Hugh Mitchell Neisler’s remarks, see Neisler 1855.
Trifolium subterraneum: subterranean clover. Trifolium polymorphum: peanut clover. Martius ed. 1840–1906 (Flora Brasiliensis), vol. 15, part 1 (Leguminosae), was edited by Bentham. In the second edition of Forms of flowers, p. xviii, CD wrote, ‘Mr. Bentham informs me that the S. American Trifolium polymorphum produces true cleistogamic flowers.’ Lespedeza is the genus of bush clovers.
For Bentham’s observations on hybrids in the related genera Cistus and Helianthemum in the family Cistaceae (rock rose), see Bentham 1826, pp. 72, 87–9.


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.

Bentham, George. 1838. On the structure and affinities of Arachis and Voandzeia. [Read 1 May 1838.] Transactions of the Linnean Society of London 18 (1841): 155–62.

Bentham, George. 1858. Handbook of the British flora; a description of the flowering plants and ferns indigenous to, or naturalized in, the British Isles. London: Lovell Reeve.

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

Neisler, Hugh Mitchell. 1855. Observations of the fructification of the Arachis hypogæa. American Journal of Science and Arts 19: 212–13.


Thanks CD for Forms of flowers. Comments on the chapter on cleistogamic flowers; offers some corrections.

Letter details

Letter no.
George Bentham
Charles Robert Darwin
Sent from
London, Wilton Place, 25
Source of text
DAR 160: 168
Physical description
4pp damaged †

Please cite as

Darwin Correspondence Project, “Letter no. 11046,” accessed on 23 September 2021,