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Letter 1703

Salter, T. B. to Darwin, C. R.

25 June 1855

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    Discusses hybrid plants he has raised, particularly hybrids between Geum urbanum and G. rivale, which are very fertile and exhibit great variability. [See Natural selection, p. 102.]

Transcription

Ryde.

June 25. 1855

My dear Sir

I was very happy to receive your letter & so far from any apology being needful, I thank you for this step towards an acquaintancy which I may hope some day to make more fully.

I have not carried my little experiments any further. They had been discontinued long before I read that little paper to our local Philosophical Society, but I felt that they ought to be recorded before they became forgott<en.> The Geum rivale in my garden was itself very little disposed to seed— I have an idea that it only seeded when fertilized with foreign pollen but the resulting hybrid is very fertile & has abundantly seeded ever since & the seedlings have come up by thousands— I have to this day growing plants and as the situation is always changing it is obvious they must be new plants. They all seed immensely & are precisely the same as the first crop of plan<ts.>

<Th>us the G. rivale fertilise< > < > the number of seeds is certainly vastly more than in the G. rivale,—if these were < > <mature> in that plant which has since died away,—but not quite so many as in G. urbanum which I have since brought into the garden.

Epilobium Montano-tetragonum is also very prolific but I cannot speak of number of seeds— I observed the generations by saving seed to the fourth year & since that they take their chance so that the hybrids, now coming up may be only the 2d generation or that of any other subsequent number.

I shall be happy to send you < >eum & capsules of Epilobium when ripe— I hope you will sow them & see the plants.

I think I might have obtained hybrid seeds of Linaria if I had tried the pollen of L. repens on the stigma of L. vulgaris instead of the reverse which is what I attempted— In the garden the plants of L. repens creep so prodigeously that they have still chance for perfecting seed.

I remain, dear Sir | Very faithfully yours | T. Bell Salter C. Darwin Esq.

    Footnotes Add

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    f1 1703.f1
    A reference to Salter 1852, a paper on the fertility of certain plant hybrids, which was first read before the Isle of Wight Philosophical Society and printed in the Phytologist. CD may have come across the paper during his bibliographic research at the Linnean Society (see letter to J. D. Hooker, 23 [June 1855]). CD's notes on Salter 1852 are in DAR 73: 88–9.
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    f2 1703.f2
    Salter's experiments had demonstrated that Epilobium roseum and Geum intermedium were the hybrid offspring of E. montanum and E. tetragonum, and G. urbanum and G. rivale, respectively. His researches further showed that these hybrids were entirely fertile and could reproduce their kind through any number of generations, unlike most hybrids which will not continue to reproduce beyond three or four generations. Salter suggested that the wild form of G. intermedium was, in fact, a species of hybrid origin (Salter 1852, p. 740).
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    f3 1703.f3
    CD referred to Salter's experimental work in Natural selection, p. 102. However, CD went on to say that, according to Hornschuch 1848, the two parent species are not always found in association with G. intermedium and that the case was more complex than mere hybrid origin. See letter to Arthur Henfrey, 17 March [1855], for CD's interest in Friedrich Hornschuch's work.
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    f4 1703.f4
    Salter described his failure to hybridise Linaria repens and L. vulgaris, but emphasised that these species could indeed be the parents of L. italica, as his friend William Arnold Bromfield had claimed in an article ‘Notes and occasional observations on some of the rarer British plants growing wild in Hampshire’, Phytologist 3 (1848): 625–6.
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