The Fertilisation of Winter-Flowering Plants

C. Darwin

Editor's Note

The correspondence on fertilisation in winter-flowering plants, begun by Alfred Bennett in the journal's first issue, continues here with a letter from Charles Darwin himself, who cautions against using bell-jars to isolate flowers from their environment (and thus any external pollination agency) because such a practice “is injurious from the moisture of the contained air”. Darwin recommends “what is called by ladies, ‘net’”, a practice which he had followed for twenty years and was able to observe fertilisation in thousands of plants. As regards Bennett's observation in Vinca , Darwin cautions that the observation of pollen falling on a stigma, and the formation of pollen tubes, is in itself “a most fallacious indication of self-fertilisation”.

WILL you permit me to add a few words to Mr. Bennett's letter, published at p. 58 of your last number? I did not cover up the Lamium with a bell-glass, but with what is called by ladies, “net”. During the last twenty years I have followed this plan, and have fertilised thousands of flowers thus covered up, but have never perceived that their fertility was in the least injured. I make this statement in case anyone should be induced to use a bell-glass, which I believe to be injurious from the moisture of the contained air. Nevertheless, I have occasionally placed flowers, which grew high up, within small wide-mouthed bottles, and have obtained good seed from them. With respect to the Vinca , I suppose that Mr. Bennett intended to express that pollen had actually fallen, without the aid of insects, on the stigmatic surface, and had emitted tubes. As far as the mere opening of the anthers in the bud is concerned, I feel convinced from repeated observations that this is a most fallacious indication of self-fertilisation. As Mr. Bennett asks about the fertilisation of Grasses, I may add that Signor Delpino, of Florence, will soon publish some novel and very curious observations on this subject, of which he has given me an account in a letter, and which I am glad to say are far from being opposed to the very general law that distinct individual plants must be occasionally crossed.

( 1 , 85; 1869)

Charles Darwin: Down, Beckenham, Kent, Nov. 13.