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Letter 2288

Gray, Asa to Darwin, C. R.

21 June 1858

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    Self-fertilisation in Fumariaceae.

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    [CD note on bees' visiting some members of Fumariaceae.]

Transcription

Dear Darwin

A word more about self-fertilization in Fumariaceæ After the tips of the outer pair of petals have separated or turned back, it is easy enough for your coadjutors the bees (whom I have never yet noticed about a Fumariaceæ) to push the cap of the inner petals to one side and reach the stigma; this is especially easy in Dicentra spectabilis & Adlumia: But in both these plants, also in Corydalis glauca & C. aurea, I generally find pollen on the stigma before the outer petals have opened, and before any insect can intermeddle. In Dicentra this is most sure, because the cup-shaped tips of the outer petals fit exactly against the sides of the crest of the inner ones, shutting all up completely until they turn back; but by this time the work is done, commonly in D. spectabilis, et,— In D. formosa or eximia if not then yet very soon afterwards. The shedding of the pollen & the opening of the outer petals is here about simultaneous, as far as I have observed.

So I must still think, that the arrangement in Fumariaceæ is intended to secure self-fertilization.

Excuse my hasty note, and believe me, as ever | Yours cordially | Asa Gray
June 21st, 1858

    Footnotes Add

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    f1 2288.f1
    Gray had claimed that Fumaria was a genus in which individuals perpetually self-fertilised, in contrast to CD's view that all organic beings must occasionally cross-fertilise (see Correspondence vol. 6, letter from Asa Gray, 7 July 1857, and letter to Asa Gray, 29 November [1857]). CD investigated the subject experimentally in June 1858 (see n. 2, below).
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    f2 2288.f2
    The note forms part of CD's record of observations made in May and June on the fertilisation of these and similar leguminous flowers by bees. The letter is bound with CD's other slips and notes on the topic in DAR 76. See also letter to J. D. Hooker, 8 [June 1858].
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