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Letter 2169

Darwin, C. R. to Gardeners' Chronicle

[before 12 Nov 1857]

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    Asks writer of an article on weeds why he supposes "there is too much reason to believe that foreign seed of an indigenous species is often more prolific than that grown at home?" The point is of interest to CD "in regard to the great battle of life which is perpetually going on all around us". Cites analogous observations by Asa Gray and J. D. Hooker. Does writer know "of any other analogous cases of a weed introduced from another land beating out … a weed previously common in any particular field or farm?"

Transcription

Will the writer of the highly remarkable article on weeds in your last Number have the kindness to state why he supposes that “there is too much reason to believe that foreign seed of an indigenous species is often more prolific than that grown at home?” Is it meant that the plant produced from the foreign seed actually produces more seed, or merely that the introduced stock is more vigorous than the native stock? I have no doubt that so acute an observer has some good reason for his belief. The point seems to me of considerable interest in regard to the great battle for life which is perpetually going on all around us. The great American botanist, Dr. Asa Gray, believes that in the United States there are several plants now naturalised in abundance from imported seed, which are likewise indigenous; and my impression is (but writing from home I cannot refer to his letter to me) that the imported stock prevails over the aboriginal. So again, Dr. Hooker in his admirable Flora of New Zealand has told us that the common Sonchus has spread extensively from imported seed, whilst the same species is likewise an aboriginal; the natives in this instance being able from trifling differences to distinguish the two stocks. Might I further ask whether it is now some years since the seed of Sinapis nigra was accidentally introduced on the farm described; and if so, whether the common Charlock still remains in lessened numbers owing to the presence of the invader, and without, as far as known, fresh seed of the invading S. nigra having been introduced?—whether, in short, it was a fair fight between the two species, ending in the victory of the Black Mustard? Would it be trespassing too much on the kindness of the writer of the article to ask whether he knows of any other analogous cases of a weed introduced from other land beating out, to a greater or lesser extent, a weed previously common in any particular field or farm? C. Darwin, Down, Bromley, Kent.

    Footnotes Add

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    f1 2169.f1
    The letter was published in Gardeners' Chronicle and Agricultural Gazette on 14 November 1857. It was written during CD's stay at Moor Park (see n. 3, below). CD returned to Down on 12 November 1857 (‘Journal’; see Correspondence vol. 6, Appendix II).
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    f2 2169.f2
    The passage to which CD refers, in the agricultural section of the Gardeners' Chronicle and Agricultural Gazette, 7 November 1857, p. 762, reads: The manner in which weeds are spread over some farms may be observed in the increase of exotic species from the use of foreign seeds, a circumstance which accounts for the increase of plants in our English Flora within the last few years. However these, as being wholly foreigners, seldom make rapid progress, whilst there is too much reason to believe that foreign seed of an indigenous species is often more prolific than that grown at home.
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    f3 2169.f3
    CD wrote the letter during his stay at Moor Park. CD underwent hydropathy at the Moor Park establishment from 5 to 12 November 1857 (‘Journal’; see Correspondence vol. 6, Appendix II). The reference is to the letter from Asa Gray, 16 February 1857.
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    f4 2169.f4
    J. D. Hooker 1853–5, 1: 152–3.
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    f5 2169.f5
    The reference is to one of the cases given in the Gardeners' Chronicle and Agricultural Gazette (see n. 2, above) illustrative of how seeds of unwanted species could be introduced into a field with manure. The article described how a large quantity of black mustard, Sinapis nigra, was unwittingly introduced into a crop of flax. In various ways the weed seeds got into the manure heaps, and the black mustard soon became widespread, ‘having nearly expelled the former common Sinapis arvensis—a circumstance which we think partly accounted for by the greater fecundity of the former, when compared with the latter’ (Gardeners' Chronicle and Agricultural Gazette, 7 November 1857, p. 762).
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    f6 2169.f6
    CD received a letter from James Buckman in response to the printed version of this letter. Although, Buckman's letter has not been found, a printed response appeared in Gardeners' Chronicle and Agricultural Gazette, 2 January 1858, p. 11, and there is an abstract of it, in CD's hand, in DAR 46.1: 41–2. The abstract describes Buckman's view that many agrarian weeds are the product of cultivation and are not found in the wild.
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