To ? 30 October [1869 or 1870]1
Down. | Beckenham | Kent. S. E.
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.2
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.3
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.4 The enclosed diagram, which is little better than a hieroglyphic, will perhaps explain what I mean.5
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
Comments on a case of crossing distant plants of Habenaria
and on hermaphroditism in hybrid plants.