CD describes first observation of gyratory motion of tendrils: explains its adaptive function is to find objects to hold on to.
Down Bromley Kent.
My dear Hooker
I have been observing, pretty carefully, a little fact which has surprised me;
& I want to know from you & Oliver whether it
seems new or odd to you; so just tell me whenever you write: it is very trifling fact so
do not think of answering on purpose I have got a plant of
Echinocystis lobata to observe the irritability of tendrils described by Asa Gray,
& which, of course, is plain enough. Having the plant
in my study I have been surprised to find that the uppermost part of each branch, (ie
the stem between the two uppermost leaves, excluding the growing tip) is
constantly and slowly twisting round, making a circle in from 1
This may be common phenomenon for what I know; but it confounded me quite when I began
to observe the irritability of the tendrils.— I do not say it is final cause,
but the result is pretty for the plant every 1
Yours affect | C. Darwin
- f1 4221.f1Daniel Oliver.
- f2 4221.f2CD refers to A. Gray 1858b, in which Asa Gray sought to corroborate from his own observations Hugo von Mohl's suggestion, first made in Mohl 1827, that the coiling of tendrils resulted from their being sensitive to touch. CD's annotated copy of the volume of the Proceedings of the American Academy of Arts and Sciences in which this paper appeared is in the Darwin Library--CUL. CD reread the article at the end of 1862, with the intention of trying `a few experiments' on the subject, and Gray sent him seeds of Echinocystis lobata for this purpose (see Correspondence vol. 10, letter to Asa Gray, 6 November , and letter from Asa Gray, 24 November 1862). CD's notes on his experiments with this species, dated 16 June -- 29 July 1863, are in DAR 157.2: 29--51.
- f3 4221.f3In his Autobiography, p. 129, CD recalled that it was Gray's paper that led him to take up the subject of climbing plants more generally, and stated:
He sent me seeds, and on raising some plants I was so much fascinated and perplexed by the revolving movements of the tendrils and stems, which movements are really very simple, though appearing at first very complex, that I procured various other kinds of Climbing Plants, and studied the whole subject.CD carried out numerous experiments on this subject in 1863 and 1864, and his paper entitled `On the movements and habits of climbing plants' was read before the Linnean Society on 2 February 1865; his observations on Echinocystis lobata are given in `Climbing plants', pp. 74--7. See also the observational and experimental notes in DAR 157.1 and 157.2.
- f4 4221.f4The reference is probably to John Horwood, gardener to CD's neighbour, George Henry Turnbull. Horwood had assisted CD with his botanical experiments over several years (see Correspondence vols. 9 and 10), and, earlier in 1863, had supervised the construction of CD's hothouse (see letter to G. H. Turnbull, [16? February 1863], and Appendix VI).