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Darwin Correspondence Project

From R. I. Lynch   [before 14 September 1877]1

[DIAG HERE]

Euphorbia jacquiniaeflora reduced

Upper leaves in nocturnal position 9 p.m

Distance between day and night positions of leaf-tips marked in red ink

Length of leaf marked in pencil

Euphorbia jacquiniaeflora

The younger leaves are subject to sleep by curving of petiole more or less throughout its length, so that the leaves are bent down to the stem and even cross it.2 The leaves are raised by straightening of petiole so that the movement is not described from a centre. The height to which the leaves are raised depends on the intensity of light and they appear to be delicately subject to its influence. In the morning the sun shines directly on the plant observed and the leaves are then highest. On one occasion they were deflected considerably by the darkness of heavy rain and this happening in the afternoon they did not afterwards recover position   On the branch roughly sketched there are about a dozen leaves below those represented and these do not appear to change position in the slightest degree

CD annotations

6.1 petiole more] underl red crayon
6.4 The … influence. 6.5] square bracket in margin, ink
6.4 on … influence. 6.5] scored red crayon

Footnotes

The date is established by the relationship between this letter and the letter to R. I. Lynch, 14 September 1877.
In Movement in plants, p. 388, CD credited Lynch with calling his attention to the fact that young leaves of Euphorbia jacquiniiflora Hook. (a synonym of Euphorbia fulgens, the scarlet plume) slept by hanging vertically downwards. See letter to R. I. Lynch, 14 September 1877.

Bibliography

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

Summary

Notes the movements of leaves of Euphorbia jacquiniaeflora in response to light intensity.

Letter details

Letter no.
DCP-LETT-11415
From
Richard Irwin Lynch
To
Charles Robert Darwin
Sent from
unstated
Source of text
DAR 209.14: 30–1

Please cite as

Darwin Correspondence Project, “Letter no. 11415,” accessed on 31 July 2021, https://www.darwinproject.ac.uk/letter/DCP-LETT-11415.xml

letter