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Darwin Correspondence Project

To W. T. Thiselton-Dyer   15 January 1880

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Jan 15— 80

My dear Dyer.

It was very very good of you to have taken such great trouble about the cotton-seeds. Some of those from Naples show this day their noses above ground, & I have no doubt will serve my purpose excellently.1 I hope my work will some day end, but new points are continually turning up.

I am now observing the germination of the Cucurbitaceous genus Megarrhiza, & it is a very curious case, for the petioles of the 2 cotyledons (which never break out of the seed-coats) unite & form a hollow tube which penetrates deeply into the ground, & becomes functionally (& structurally as far as surface is concerned) a root; the plumule bursts the tube at a depth of 2–3 inches beneath the ground & then rises to the surface.—2

Ever yours sincerely | Ch. Darwin.

You are an unfortunate man: writing about Megarrhiza has made me think that I ought to look again at the germinating seeds of Trichosanthes anguina or I daresay any Trichosanthes, for I record in my notes that “cotyledons fleshy almost like hypogean ones”. Therefore the hypocotyledonous stem ought not to be provided with that wonderful peg or heel by which the seed-coats of most other Cucurbitaceæ are torn apart beneath the ground, & which I was delighted to find quite absent in Megarrhiza.3 Am I not a superb bore?!

Can you give me seeds of Trichosanthes; but do not write.—


CD had requested cotton seeds in his letter to W. T. Thiselton-Dyer, 20 November 1879 (Correspondence vol. 27). CD studied sleep in the cotyledons of ‘Naples’ cotton; his notes from 21 January to 17 February 1880 are in DAR 209.9: 16.
CD studied germination in Megarrhiza californica, a synonym of Marah fabacea, California manroot; Cucurbitaceae is the family of gourds and squashes. He observed the plant between 14 and 30 January 1880 (his notes are in DAR 209.6: 105–15; his observations of the plumule, the stem immediately above the cotyledons, are in DAR 209.6: 107 and DAR 209.6: 109). See also Movement in plants, pp. 81–3.
Trichosanthes anguina is a synonym of T. cucumerina, snake gourd. CD had noted its ‘thick & fleshy’ cotyledons in April 1877 (DAR 209.9: 99); he made further observations of the peg or heel of the radicle later in January 1880 (DAR 209.6: 165). See also Movement in plants, pp. 102–6.


Thanks for cotton seeds.

Germination of Megarrhiza.

Letter details

Letter no.
Charles Robert Darwin
William Turner Thiselton-Dyer
Sent from
Source of text
Royal Botanic Gardens, Kew (Darwin: Letters to Thiselton-Dyer, 1873–81: ff. 199–200)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 12424,” accessed on 18 August 2022,