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Darwin Correspondence Project

From Asa Gray   5 December 1876

Herbarium of Harvard University, | Botanic Garden, Cambridge, Mass.

Dec. 5 1876

Dear Darwin

Your postal of 20th Nov. received.1

I know nothing about the Indian species of Hottonia. Somebody saying (I can’t at this moment tell who*) that H. palustris is dimorphous; I thought I had it clear that our H. inflata was too—but only from dried specimens. (I have not for years seen it growing. I must get it & have it looked to.) I fear I judged so hastily from finding some young fruit tipped with extremely short style, others with style of fair length, but, as you know, short indeed compared with either form of H. palustris.— But now, on looking out various flowers, I see it must be, as you say, not structurally dimorphic.2 And turning to a forgotten observation of dear old Torrey I see what misled me.3

I have Torrey’s note—the essential part of it copied for you. The subsessile stigmas must have belonged to cleistogenous flowers.

Torrey cannot mean of course—that all the flowers of H. inflata are cleistogenous,—only some of the earlier ones. All the later ones at least open out their well-formed corolla, &c—

Curious that one species should take pains to close-fertilize some flowers—the other to cross all. 〈15 lines excised

Now I want to beg of you to consider about a name for this kind of thing,—on which, as a good judge, you could Bentham,—or indeed, Hooker,4 if he can give it attention.—

This matter will need to come into generic or specific 〈15 lines excised

characters, and therefore wants a terse and unambiguous mode of expression in a single word.

My old expression 30 or so years ago diœcio-dimorphous—you reasonably objected to implying separation of sexes (which tho’ it need not.) Yours of dimorphous should be, as the lawyers say void for vagueness, there being plenty of other kinds of dimorphism in flowers.

Hildebrands, of heterostylous—the difference being in other things as well as style, and, I think, possible sometimes not in the style. The term will not work well in characters, whether Latin or English.— I have proposed, accordingly—in a little article not yet published—to use the term heterogone in other forms heterogonous in Latin Flores heterogoni, with the counterpart homogone, homogonous, Flores homogoni.

This means, you see, explicitly, diverse genitalia, and the [G[goni,i]G] is used as in the common botanical term perigonium.5 I wish you would adopt this. I am very glad you will re-edit & collect those papers.

Yours ever, | A. Gray

*Oh yes, I now have Scott’s & your paper before me!6


Bulletin of the Torrey Botanical Club, vol. II. 22—June 1871.7

“Note on Hottonia inflata, Ell.

xxx About three weeks ago xx it was just commencing to throw up its scapes, in which state I received a number of specimens & placed them in a glass vase of water, so that I had an opportunity of watching their development in my study. The scapes have grown to the height of 4 or 5 inches, & have produced numerous whorls of flowers. Their corolla is scarcely more than a line and a half in length, & its border never expands. At a very early age, when the flower buds are barely formed, fertilization takes place, & the corolla is detached from its base by the enlargement of the ovary, on the summit of which it remains, like a little cap, until the fruit is mature. Fertilization must take place without any aid from without, for the corolla does not open, the stamens & pistil being closely shut in, and the anthers being directly in contact with the stigma. xxx

John Torrey

Columbia College | New York—June 6, 1871.”


Dimorphism and cleistogamy in Hottonia.

AG wants new, unambiguous term for what is now referred to as "dimorphism", "dioecio-dimorphism", or "heterostyly"; proposes "heterogone".

Sends an excerpt from Bulletin of Torrey Botanical Club 2 (June 1871) on Hottonia inflata.

Letter details

Letter no.
Asa Gray
Charles Robert Darwin
Sent from
Herbarium of Harvard
Source of text
DAR 165: 192, DAR 111: A92
Physical description
5pp inc , encl 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 10699,” accessed on 28 April 2017,

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