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Letter 6961A

Darwin, C. R. to unidentified

30 Oct [1869 or 1870]

    Summary Add

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    Comments on a case of crossing distant plants of Habenaria

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    and on hermaphroditism in hybrid plants.


Down. | Beckenham | Kent. S. E.

Oct. 30th.

My dear Sir

The case of the Habenaria is very interesting as shewing how distant plants may be crossed; & I wish I had known of it before drawing up the notes of which I send a copy by this post.

The Lychnis-case well deserves investigation; but I doubt whether the bi-sexual condition can be the result of crossing (tho' this wd please me much;) for Gärtner crossed the two sp. repeatedly, & cd hardly have failed to have observed in the hybrids a tendency to hermaphroditism.

If the smaller grains of pollen are of equal size & really sound, I shd suspect a reversion to a dimorphic condition, like that of Primula. I have long had reason to suspect that some dioicous plants originate from the suppression of the reversed sexes in the 2 forms of dimorphic plants. The enclosed diagram, which is little better than a hieroglyphic, will perhaps explain what I mean.

Your hermaphrodite plants ought all to be transplanted into a garden, carefully observed, the small-grained pollen experimented on, with insects, of course, carefully excluded.

This is what I shd do if I had the plants, & I think that you wd find it worth while to observe them with care—

Pray believe me | My dear Sir | yours very faithfully | Ch. Darwin

    Footnotes Add

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    f1 6961a.f1
    The date range is established by the form of the address with `Bromley' crossed out and `Beckenham' added, which CD used between April 1869 and May 1871.
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    f2 6961a.f2
    The notes CD sent have not been identified. CD's notes on the floral morphology of Habenaria (bog orchids) are in DAR 205.8: 9--10. The species of Habenaria studied by CD are now in the genera Platanthera and Coeloglossum, both known to hybridise intergenerically in nature (see Orchids, pp. 76--8, 83--92, and Dressler 1981, p. 189).
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    f3 6961a.f3
    Lychnis is the genus of campions. For Karl Friedrich von Gärtner's results in crossing different species of Lychnis, see Gärtner 1849, pp. 218--19 (see also Natural selection, pp. 393--4).
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    f4 6961a.f4
    For more on CD's interest in rudimentary sexual organs found in flowers of Lychnis dioica (now Silene dioica, red campion), see Correspondence vols. 9 and 10. In Cross and self fertilisation, pp. 410--11, CD discussed the possible causes for the separation of sexes in L. dioica.
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    f5 6961a.f5
    The diagram has not been found.
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