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Darwin Correspondence Project

From A. W. Bennett   3 May 1869

Lancaster Villa | York Road, Upper Holloway | London N.

May 3rd 1869

Dear Sir

Tempted by the kindness of your reply to my previous note, I venture to send you by this post my notes made during the past winter & spring on the fertilization of certain plants flowering at those seasons of the year, with the accompanying drawings.1 I should not think of publishing the observations as a series until they have extended over a much wider range, or I have had the opportunity of confirming them by a second series;2 but it would be a great assistance to me if the accuracy of any of them were tested by an independent observer; & I venture to hope you may be able to give me some valuable advice as to the best direction in which to prosecute them, or even as to whether any scientific end will be gained by following them.

My observations so far have led me to the following conclusions (subject of course to correction from a wider series of observations) as to the different classes into which winter-flowering plants may be divided.

1. Those which flower & fructify abundantly through the whole year equally in Dec. & Jan to the summer. These I find to be self-fertilized & generally in the lead at whatever time of the year they flower; & this I take to be the circumstance which adapts them to so long a period of flowering not requiring insect-agency for their fertilization, e.g. Lamium album, Veronica Buxbaumii, Euphorbia Poplus.3

2. Those which normally flower in the spring; but in mild seasons are found not infrequently in the winter; these are cross-fertilized; e.g. Sinapis arvensis, Fumaria officinalis 4

3. Very early spring-flowering plants; these are generally either showy or scented, attracting the earliest spring insects, & are cross fertilized. e.g. Viola odorata, Galanthus nivolis.5

4. Plants flowering in the depth of winter, but natives of warmer climates, where there are probably plenty of insects in the winter; these are cross-fertilized; e.g. Chimonanthus fragrans & Eranthis hyemalis where the provisions for crossing are even more perfect that in Parnassia, & which appears never to fructify in our gardens.6

The most interesting observations to myself have been those on the three species of Euphorbia, Peplus, Heliscopia, & amygdaloides; the two former, genuine winter-flowering plants being apparently self-fertilized, i.e. the pistil from the stamens in the same head of flowers; while in the latter, which never flowers before April, the pistil appears to be fertilized from the male heads of flowers.7

You will find Eranthis hyemalis, the Christmas Rose8 among the plants in which some observations have been made

I am specially curious about the fertilization of Ruscus.9 In most unisexual winter flowering plants, e.g. Corylus avellana,10 there appears to be special provision for fertilization in the enormous preponderance of male flowers over female, & the manner in which the former are hung, so that the pollen is freely dispersed in clouds by every breath of wind. In the Ruscus on the contrary, which is generally considered to be diœcious, there appears to be no such preponderance, & the excessively rigid stems, growing under the shelter of shrubs & under-wood, would seem to be peculiarly inaccessible to the action of the wind. I found abundance of flowers out last winter in the Surrey heaths during the last week of December, & there were a fair number of the previous year’s berries still remaining on the female plants.

I should be much obliged if you would kindly return the notes & drawings when you have had leisure to glance over them, & must really apologize for troubling you with so long a letter as this

& remain | yrs respectfully | Alfred W. Bennett

C. Darwin Esq

CD annotations

3.1 1. Those … Poplus. 3.5] double scored pencil
Top of letter: ‘See 2d paper Lamium album’ pencil, ringed pencil; ‘Gorse’ pencil, ringed pencil; ‘Does this not indicate sterile at one period & fertile at next’ pencil

Footnotes

CD’s letter has not been found, but it was evidently a reply to the letter from A. W. Bennett, 22 April 1869. The notes and drawings that Bennett refers to have not been found.
Bennett published ‘On the fertilisation of winter-flowering plants’ on 4 November 1869 in the inaugural issue of Nature (Bennett 1869). He discussed observations made in the winter of 1868 to 1869. CD’s annotated copy of the article is in DAR 139.13: 1.
Lamium album is white dead-nettle, Veronica buxbaumii (now V. persica) is bird’s eye speedwell, and Euphorbia peplus is petty spurge (see Bennett 1869, p. 11).
Sinapis arvensis is charlock; Fumaria officinalis is common fumitory (see Bennett 1869, p. 11).
Viola odorata is the sweet violet; Galanthus nivalis is the common snowdrop.
Chimonanthus fragrans (now C. praecox) is wintersweet or Japanese allspice; Eranthis hyemalis is winter aconite (see Bennett 1869, p. 12). For Bennett’s observations on Parnassia palustris (grass of Parnassus), see the letter from A. W. Bennett, 22 April 1869 and n. 1.
Euphorbia helioscopia is sun spurge; E. amygdaloides is wood spurge (see Bennett 1869, pp. 12–13).
See above, n. 6; ‘Christmas rose’ is now the common name for Helleborus niger.
Ruscus is a genus of dioecious evergreen shrubs formerly in the family Liliaceae but now in the family Ruscaceae.
Corylus avellana is hazel.

Bibliography

Bennett, Alfred William. 1869. On the fertilisation of winter-flowering plants. Nature 1: 11–13.

Summary

Sends CD some notes [missing] on the mode of fertilisation of winter-flowering plants, and outlines his conclusions regarding the different types of winter-flowerers and the means by which they are fertilised.

Letter details

Letter no.
DCP-LETT-6724
From
Alfred William Bennett
To
Charles Robert Darwin
Sent from
Upper Holloway
Source of text
DAR 76: B176–7
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6724,” accessed on 19 April 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-6724.xml

Also published in The Correspondence of Charles Darwin, vol. 17

letter