skip to content

Darwin Correspondence Project

From C. E. Bessey   28 June 1877

Iowa Agricultural College. | Ames,

June 28th 1877

My dear Mr. Darwin.

Dr Gray forwarded to me your letter to him of date of June 4th—in which you so pleasantly refer to my notes on Lithospermum longiflorum, and promise me a copy of your new book.1

I shall be delighted to receive it, and shall be glad to follow up its hints.

I have been watching our little Oxalis violacea for some time and have partially put into shape my last year’s observations, in a paper read before the Iowa Academy of Sciences at its May meeting in 1877.2   You are, no doubt, familiar with the heterostylism so common in this genus.3 I carefully measured the lengths of Calyx, Corolla, pistils and the two rows of Stamens, and found a wonderful correspondence




This diagram will show the relation of the parts in each form, and also their relation to each other. In my paper I say “The tendency must be towards dioe-ciousness, for, the long pistils of A and the long stamens of B are the ones (according to my view) which perpetuate their kind to the greatest extent.”

I further say that these and other observations “incline me to believe that this kind, of dimorphism is to be looked upon as but the early stage of a change which eventually will result in the complete separation of the sexes; that is, in complete dioe-ciousness.”

I will communicate to Dr. Gray (as I have promised to do) the results of further observations on this plant and Lithospermum, and he will no doubt show them to you if they appear worth your notice.4

Again thanking you for your pleasant words | I am | Very truly | Your obt servant | C. E. Bessey.


See letter to Asa Gray, 4 June [1877] and n. 2. Bessey’s name appears on CD’s presentation list for Forms of flowers (see Appendix IV).
Bessey’s paper on Oxalis violacea (violet wood-sorrel), a species native to North America, has not been found.
CD’s interest in dimorphism in Oxalis began in 1861 (see Correspondence vols. 9 and 10); he published the results of his observations in Forms of flowers, pp. 169–83, 321–4.
Bessey went on to publish on Lithospermum longiflorum (a synonym of Lithospermum incisum, fringed gromwell); he concluded that the species was not dimorphic, but that it presented a possible case of incipient heterostyly (Bessey 1880). See letter from Asa Gray, 30 March 1877 and n. 2.


Bessey, Charles Edwin. 1880. The supposed dimorphism of Lithospermum longiflorum. (L. angustifolium Michx. of Gray’s synoptical flora.) American Naturalist. 14: 417–21.

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

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


Has heard through Asa Gray of CD’s interest in his work on Lithospermum and Oxalis. Thinks dimorphism in Oxalis is but early stage toward complete separation of sexes.

Letter details

Letter no.
Charles Edwin Bessey
Charles Robert Darwin
Sent from
Iowa Agric. Coll., Ames
Source of text
DAR 160: 178
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 11021,” accessed on 25 September 2021,