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Darwin Correspondence Project

To ?   30 October [1869 or 1870]1

Down. | Beckenham | Kent. S. E.

Oct. 30th.

My dear Sir

The case of the Habenaria is very interesting as shewing how distant plants may be crossed; & I wish I had known of it before drawing up the notes of which I send a copy by this post.2

The Lychnis-case well deserves investigation; but I doubt whether the bi-sexual condition can be the result of crossing (tho’ this wd please me much;) for Gärtner crossed the two sp. repeatedly, & cd hardly have failed to have observed in the hybrids a tendency to hermaphroditism.3

If the smaller grains of pollen are of equal size & really sound, I shd suspect a reversion to a dimorphic condition, like that of Primula. I have long had reason to suspect that some dioicous plants originate from the suppression of the reversed sexes in the 2 forms of dimorphic plants.4 The enclosed diagram, which is little better than a hieroglyphic, will perhaps explain what I mean.5

Your hermaphrodite plants ought all to be transplanted into a garden, carefully observed, the small-grained pollen experimented on, with insects, of course, carefully excluded.

This is what I shd do if I had the plants, & I think that you wd find it worth while to observe them with care—

Pray believe me | My dear Sir | yours very faithfully | Ch. Darwin


The date range is established by the form of the address with ‘Bromley’ crossed out and ‘Beckenham’ added, which CD used between April 1869 and May 1871.
The notes CD sent have not been identified. CD’s notes on the floral morphology of Habenaria (bog orchids) are in DAR 205.8: 9–10. The species of Habenaria studied by CD are now in the genera Platanthera and Coeloglossum, both known to hybridise intergenerically in nature (see Orchids, pp. 76–8, 83–92, and Dressler 1981, p. 189).
Lychnis is the genus of campions. For Karl Friedrich von Gärtner’s results in crossing different species of Lychnis, see Gärtner 1849, pp. 218–19 (see also Natural selection, pp. 393–4).
For more on CD’s interest in rudimentary sexual organs found in flowers of Lychnis dioica (now Silene dioica, red campion), see Correspondence vols. 9 and 10. In Cross and self fertilisation, pp. 410–11, CD discussed the possible causes for the separation of sexes in L. dioica.
The diagram has not been found.


Comments on a case of crossing distant plants of Habenaria

and on hermaphroditism in hybrid plants.

Letter details

Letter no.
Charles Robert Darwin
Source of text
King Edward VI High School, Stafford
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6961A,” accessed on 22 June 2018,

Also published in The Correspondence of Charles Darwin, vol. 17