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Darwin Correspondence Project

To Asa Gray   19 April 1880

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

April 19th. 1880

My dear Gray

It was very good of you to send me Mr. Rattan’s letter which has interested me extremely.1 I suppose that I may give some of his statements. It seems almost certain that the protection of the plumule from frost has determined the curious mode of germination; & this agrees well with the drawing down in winter of so many seedlings by the contraction of their radicles. But I still think the protection of the enlarged roots from being devoured is probably a secondary advantage thus gained.2 The “crocks” explain the behaviour in your first case.3

What a curious fact of Mr. Rattan’s,—that of the confluent petioles growing out horizontally without coming into contact with the bottom of the shallow box. From what I have observed with other seedlings I believe I understand the cause, but it is too long a story.4 I wish I had a score of germinating seeds to experimentise on.—

Very many thanks for P. Card about roots of Ipomœa leptophylla: I have tried in vain to get seeds of I. pandurata from Kew.5

Ever yours very truly | Ch. Darwin

Mr Rattan seems to be a real good observer, & that is a rare species of animal.—

Footnotes

1
With his letter to CD of 4 April 1880, Gray had enclosed a letter from Volney Rattan with observations on the germination of Megarrhiza californica (a synonym of Marah fabacea, California manroot).
2
CD had hypothesised that the tubular petioles of Megarrhiza californica acted functionally like a root to protect the (true) enlarged root against predators (see letter to Asa Gray, 19 January 1880). Rattan had observed that an unburied portion of one sprout was blackened by frost, but the buried part was fresh, leading him to conclude that the plumule would have survived (see letter from Asa Gray, 4 April 1880, enclosure). CD mentioned Rattan’s observation on the mode of germination in Movement in plants, pp. 82–3.
3
Gray had initially doubted CD’s description of the movement of the petioles to penetrate the ground in the germination of Megarrhiza californica (see letter from Asa Gray, 3 February 1880 and n. 2).
4
In his letter to Gray, Rattan had included drawings of the manner of growth of the petioles during the germination of seeds that he had planted in a shallow box (see letter from Asa Gray, 4 April 1880, enclosure).

Bibliography

Movement in plants: The power of movement in plants. By Charles Darwin. Assisted by Francis Darwin. London: John Murray. 1880.

Summary

Thanks for the letter from Volney Rattan [see 12553].

Discusses protective adaptation of seedlings from frost.

Letter details

Letter no.
DCP-LETT-12582
From
Charles Robert Darwin
To
Asa Gray
Sent from
Down
Source of text
University of California, Berkeley, The Bancroft Library (BANC MSS 74/78 z)
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 12582,” accessed on 26 September 2022, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-12582.xml

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