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Darwin Correspondence Project

To Daniel Oliver   9 April [1861]1

Down Bromley Kent

Ap. 9th.

My dear Sir

Anytime when you happen to write to me, but not write on purpose, please tell me name of enclosed Fumaria or Corydalis— it grows in my garden in open air.— It exhibits a very little, pretty adaptation to Bees.—2 The long nectary alone secretes honey; & when Bees are sucking, they push off the hood over the pistil & stamens; & then the pistil & stamens (curved to side of nectary) are rubbed against Bee’s belly, & so cross would often be effected. As long as hood is kept pushed off the pistil & stamens, it keeps open, & when it springs back, it beautifully snaps together & again encloses the pistil & stamens.— Now if you push the opposite way, which Bees never do, as there is no nectar on that side, it is with difficulty that the hood can be pushed off the pistil & stamens, but when this is effected, the hood does not keep open, & so can never again enclose & protect the pistil & stamens.3 It is worth looking at fresh flower, & trying with a pin.—

In Dielytra, where nectar is on both sides, pistil is straight, & the hood can be pushed off both sides with equal facility, as I have seen Bees do.— Here is much cry & little wool!4

Yours very sincerely | C. Darwin


The year is given by a note dated 9 April 1861 relating to Fumaria (see n. 3, below).
CD had begun experiments on the pollination mechanisms of Fumariaceae in 1858, though he did not publish on this topic until many years later. See Nature 9 (1874): 460 (Collected papers 2: 182–3) and Cross and self fertilisation.
The observation referred to in the letter is described in a note dated 9 April 1861 (DAR 76 (ser. 2): 17): I have been looking at that Fumariæ dingy purple with one long nectary & one rudimentary— (the latter alone [interl] white). Plenty of sweet nectar in the long one; none in short.— Pistil curved to long-nectary side.— Here [after del ‘I fi’] is beautiful contrivance, if hood be forced off, as Bee would in sucking, it keeps wide open as long as open & when it springs back it beautifully encloses, as at first, the anthers— It can be pushed the other way with difficulty, but then there is this marked difference   the hood does not keep open; so that when loosed it does not enclose pistil & stamens, which are thus no longer protected.... Mr Oliver believes Corydalis solida (=C. bulbosa)
This proverb from the Latin is equivalent to ‘much ado about nothing’.


Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.

Cross and self fertilisation: The effects of cross and self fertilisation in the vegetable kingdom. By Charles Darwin. London: John Murray. 1876.


Asks DO to identify enclosed Fumaria or Corydalis flower, with springing hood adaptation.

Letter details

Letter no.
Charles Robert Darwin
Daniel Oliver
Sent from
Source of text
DAR 261.10: 6 (EH 88205990)
Physical description
ALS 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 3499,” accessed on 7 June 2023,

Also published in The Correspondence of Charles Darwin, vol. 9