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Darwin Correspondence Project

To Asa Gray   30 May [1875]1

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

May 30th

My dear Gray

Would you be so kind as to get & send me this summer a packet of seeds of Nessæa verticillata. I want to raise seedlings from illegitimate unions to see if the seedlings are sterile like true Hybrids & like the illeg. offspring of Lythrum; for the fact seems to me all important.—2

Ever yours | C. Darwin


The year is established by the printed stationery, which is of a sort used by CD from 18 November 1874, and by CD’s statement in February 1875 that he intended to carry out more research on dimorphic and trimorphic plants (see n. 2, below).
Gray had sent CD Nesaea seeds in 1862 (see Correspondence vol. 10, letter from Asa Gray, 27 October 1862). Nesaea verticillata (a synonym of Decodon verticillatus) is swamp loosestrife, native to eastern North America. CD had first experimented on Lythrum salicaria (purple loosestrife) in 1862 when investigating the connection between dimorphism and sterility, and had published the results in ‘Three forms of Lythrum salicaria and ‘Illegitimate offspring of dimorphic and trimorphic plants’ (see Correspondence vol. 10). He was considering carrying out further research and revising these papers for inclusion in Cross and self fertilisation (see letter to J. V. Carus, 7 February 1875). The reworked papers eventually appeared as part of Forms of flowers, but there is no discussion of Nesaea verticillata beyond what was originally included in ‘Three forms of Lythrum salicaria.


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.

‘Illegitimate offspring of dimorphic and trimorphic plants’: On the character and hybrid-like nature of the offspring from the illegitimate unions of dimorphic and trimorphic plants. By Charles Darwin. [Read 20 February 1868.] Journal of the Linnean Society of London (Botany) 10 (1869): 393–437.

‘Three forms of Lythrum salicaria’: On the sexual relations of the three forms of Lythrum salicaria. By Charles Darwin. [Read 16 June 1864.] Journal of the Linnean Society (Botany) 8 (1865): 169–96. [Collected papers 2: 106–31.]


Wants seeds of Nesaea verticillata for crossing experiments to see whether seedlings from "illegitimate unions" are sterile like true hybrids.

Letter details

Letter no.
Charles Robert Darwin
Asa Gray
Sent from
Source of text
Archives of the Gray Herbarium, Harvard University (121)
Physical description
ALS 1p

Please cite as

Darwin Correspondence Project, “Letter no. 10002,” accessed on 16 July 2024,

Also published in The Correspondence of Charles Darwin, vol. 23