RECORD: Darwin, C. R. 1863.05-06.15. Broom / Dichogam. CUL-DAR76.B56-B57. Edited by John van Wyhe (Darwin Online, http://darwin-online.org.uk/)

REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 12.2022. RN1

NOTE: See record in the Darwin Online manuscript catalogue, enter its Identifier here. Reproduced with permission of the Syndics of Cambridge University Library and William Huxley Darwin. The volumes CUL-DAR 76-79 contain material for Darwin's book Cross and self fertilisation (1876).


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Broom. May 1863 Dichogam —

Flowers kept several days in water, even shorter stamen did not protrude. Bees visit fresh flower & a touch cause short anther to protrude; these will dust under side of thorax. Then bee pushes harder, or flies to older flower, & pushes down keel & out flies pistil & longer an stamens which by elasticity causes stigma to strike its back, & pistil carries mass of pollen, with which back is dusted yellow; & thus stigma is dusted with own pollen & that from otherflowers— Bee flies away, the elasticity of pistil causes it to curve more completely, so that stigma lies now near to shorter stamens & stigma is upturned & will be by next bee rubbed against

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[Figure] after flower touched

[Figure] after protrusion of long stamens & pistil

Standard supposed to be transparent wing-petals removed

[57]

under side of thorax, which we have seen get dusted with pollen from shorter stamens. Thus the upper & lower surface of thorax get dusted & at first stigma rubs upper surface & then lower surface!

Ultimately pistil curls still more subsequently to its fertilisation

June 2d The 4 of 5 fl. fertilised twice May 23d have dropped off. I fertilised 3 more.

June 15th Only 1 out of these 8 flowers has produced pod; so though this order very difficult to fertilise — this throws doubts on whole case. The great branch under net, has only produced 6 or 7 pods & these close to net, against which flowers were pressed: it is possible that even Bees may have sucked some of these

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flowers; but I think mere friction— a bush in much darker shade than net cd. have caused has set plenty of pods.— A heavy gale of wind by beating flowers latterly sprung some of flowers, but I may safely say do not go off if undisturbed.

It is less certain that they cannot fertilise themselves.— possibly, but not probably net in some way injurious. —


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Citation: John van Wyhe, ed. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

File last updated 1 June, 2023