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Darwin Correspondence Project

To Asa Gray   20 December 1876

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

Dec 20. 1876

My dear Gray.

Very many thanks about Hottonia.1 You mention Forsythia in the American Naturalist, and I have just examined dried flowers from Kew, & find that F. suspensa is beautifully dimorphic; so I have got a new family.2 I have been thinking about your proposed new terms, and I cannot for very shame change again   I have used this term in two or three printed articles, and it is used by several German & Italian writers. Kuhn objected to the term on the same ground as you do; but no one objects to Vertebrata, because it includes an animal without vertebræ. Moreover heterostyled seems to me more definite than heterogone, as the latter would apply to di & monœcious & to polygamous plants. I am of course not able to appreciate the difficulty of working in the term in systematic works; but Thwaites speaks of forma stylosa, & why may not a species be called hetero stylosa?3

However this may be it really would be too ridiculous for me to change again, so I remain Your affectionate & obstinate friend | Charles Darwin


See letter from Asa Gray, 5 December 1876; Gray had provided information about Hottonia palustris (the water violet) and H. inflata (American featherfoil).
Gray had discussed evidence of dimorphism in Forsythia suspensa (weeping forsythia), and F. viridissima (green-stem forsythia), noting that only one form of each species existed in Cambridge, Massachusetts, in American Naturalist 7 (1873): 422–3. CD cited the note in Forms of flowers, p. 117.
See letter from Asa Gray, 5 December 1876 and n. 5. Friedrich Hildebrand had introduced the term ‘heterostyled’ to describe plants with two or three forms of flowers, having styles of different lengths relative to their stamens, in Hildebrand 1867. CD had used it in Variation 2d ed. and in Cross and self fertilisation. Max Kuhn had objected on the grounds that the differences between the flower-forms were not restricted to differences in length of style (Kuhn 1867, p. 66; see also Forms of flowers, p. 244). George Henry Kendrick Thwaites used stylosa and staminea (glossed as stylosa: with longer alternate stamens, shorter style, and staminea: with stamens of equal length, longer style) in his description of the two forms of Sethia acuminata (a synonym of Erythroxylum macrophyllum) in Thwaites 1858–64, 5: 54; see also Forms of flowers, p. 122.


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.

Kuhn, Max. 1867. Einige Bemerkungen über Vandellia und den Blüthenpolymorphismus. Botanische Zeitung 25: 65–7.

Thwaites, George Henry Kendrick. 1858–64. Enumeratio plantarum Zeylaniæ: an enumeration of Ceylon plants, with descriptions of the new and little-known genera and species, observations on their habits, uses, native names, etc. Assisted in the identification of the species and synonymy by J. D. Hooker. 5 pts. London: William Pamplin; Dulau & Co.

Variation 2d ed.: The variation of animals and plants under domestication. By Charles Darwin. 2d edition. 2 vols. London: John Murray. 1875.


Thanks for information about Hottonia.

Has found dimorphism in Forsythia.

Considers AG’s arguments on different terms for dimorphism, but cannot change to using the proposed new term [see 10699].

Letter details

Letter no.
Charles Robert Darwin
Asa Gray
Sent from
Source of text
Archives of the Gray Herbarium of Harvard University (116)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10728,” accessed on 14 April 2021,

Also published in The Correspondence of Charles Darwin, vol. 24