To W. H. Harvey   24 December [1856]1

Down Bromley Kent

Dec. 24th

My dear Sir

Dr. Hooker2 thinks you would not grudge giving me a little bit of information; I want only so much as would go in the compass of a short note.— It regards the higher marine plants, of which the male & female elements of reproduction are pretty clearly made out.— Are such plants generally or universally dioecious, or monoecious, or hermaphrodite in the sense that the male & female organs are so close together that the male element & of the same individual would apparently always fertilize the adjoining female, as appears to be the case (whether or not really) in common hermaphrodite phanerogams.—3

Can you answer this question? If so I shd be very much obliged for an answer at your leisure.— I have long been interested in following out Andrew Knight’s notion that all plants occasionally cross with another individual.—4

I was very glad to hear some time ago of your safe return after your long voyage.—5

When last I saw you it was at Oxford, & the remembrance of that very pleasant week to me, often recurs to my memory.—6

Pray believe me, My dear Sir | Yours very sincerely | Charles Darwin

1
The year is established by the relationship between this letter and the letter from W. H. Harvey, 3 January 1857 (Correspondence vol. 6).
3
Seaweeds, or marine algae, are cryptogams with no conspicuous flowers. Although the mode of reproduction had not yet been determined for all species (Sachs 1875a, p. 211), Gustave Adolphe Thuret had established that some reproduced sexually (Thuret 1854–5; see also Correspondence vol. 6, letter to J. D. Hooker, 21 [May 1856] and n. 6). Phanerogams, in contrast to cryptogams, have obvious flowers.
4
Thomas Andrew Knight had argued that the vigour of new plant varieties showed that ‘nature intended that a sexual intercourse should take place between neighbouring plants of the same species’ (Knight 1799, p. 202).
5
Harvey had recently returned from a three-year collecting trip around the world during which he had made extensive collections of algae from Ceylon (Sri Lanka) and Australia (Silva et al. 1996, p. 3).
6
Harvey and CD probably met at the British Association for the Advancement of Science meeting held in Oxford in the last week of June 1847; for CD’s memories of that week see, for example, Correspondence vol. 4, letter to J. S. Henslow, [26 September 1849].

Manuscript Alterations and Comments

1.2 I] after del ‘Ho’
1.2 short] interl
1.4 pretty] interl

Please cite as “DCP-LETT-2021F,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-2021F