tion>
Charles Darwin
The Movements and Habits of Climbing Plants
Published by Good Press, 2019
EAN 4057664598011
Table of Contents
THE MOVEMENTS AND HABITS OF CLIMBING PLANTS.
CHAPTER III. Tendril-Bearers .
CHAPTER IV. Tendril-Bearers —(continued) .
CHAPTER V. Hook and Root-Climbers.—Concluding Remarks .
PREFACE
This Essay first appeared in the ninth volume of the ‘Journal of the Linnean Society,’ published in 1865. It is here reproduced in a corrected and, I hope, clearer form, with some additional facts. The illustrations were drawn by my son, George Darwin. Fritz Müller, after the publication of my paper, sent to the Linnean Society (Journal, vol. ix., p. 344) some interesting observations on the climbing plants of South Brazil, to which I shall frequently refer. Recently two important memoirs, chiefly on the difference in growth between the upper and lower sides of tendrils, and on the mechanism of the movements of twining-plants, by Dr. Hugo de Vries, have appeared in the ‘Arbeiten des Botanischen Instituts in Würzburg,’ Heft. iii., 1873. These memoirs ought to be carefully studied by every one interested in the subject, as I can here give only references to the more important points. This excellent observer, as well as Professor Sachs, [iv] attributes all the movements of tendrils to rapid growth along one side; but, from reasons assigned towards the close of my fourth chapter, I cannot persuade myself that this holds good with respect to those due to a touch. In order that the reader may know what points have interested me most, I may call his attention to certain tendril-bearing plants; for instance, Bignonia capreolata, Cobæa, Echinocystis, and Hanburya, which display as beautiful adaptations as can be found in any part of the kingdom of nature. It is, also, an interesting fact that intermediate states between organs fitted for widely different functions, may be observed on the same individual plant of Corydalis claviculata and the common vine; and these cases illustrate in a striking manner the principle of the gradual evolution of species.
APPENDIX TO PREFACE (1882).
Since the publication of this Edition two papers by eminent botanists have appeared; Schwendener, ‘Das Winden der Pflanzen’ (Monatsberichte der Berliner Akademie, Dec. 1881), and J. Sachs, ‘Notiz über Schlingpflanzen’ (Arbeiten des botanischen Instituts in Würzburg, Bd. ii. p. 719, 1882). The view “that the capacity of revolving, on which most climbers depend, is inherent, though undeveloped, in almost every plant in the vegetable kingdom” (‘Climbing Plants,’ p. 205), has been confirmed by the observations on circumnutation since given in ‘The Power of Movement in Plants.’
ERRATA.
On pp. 28, 32, 40, 53, statements are made with reference to the supposed acceleration of the revolving movement towards the light. It appears from the observations given in ‘The Power of Movement in Plants,’ p. 451, that these conclusions were drawn from insufficient observations, and are erroneous.
THE MOVEMENTS AND HABITS OF CLIMBING PLANTS.
CHAPTER I.
Twining Plants.
Introductory remarks—Description of the twining of the Hop—Torsion of the stems—Nature of the revolving movement, and manner of ascent—Stems not irritable—Rate of revolution in various plants—Thickness of the support round which plants can twine—Species which revolve in an anomalous manner.
I was led to this subject by an interesting, but short paper by Professor Asa Gray on the movements of the tendrils of some Cucurbitaceous plants. [1a] My observations were more than half completed before I learnt that the surprising phenomenon of the spontaneous revolutions of the stems and tendrils of climbing plants had been long ago observed by Palm and by Hugo von Mohl, [1b] and had subsequently been the subject of two memoirs by Dutrochet. [1c] Nevertheless, I believe that my observations, founded on the examination of above a hundred widely distinct living species, contain sufficient novelty to justify me in publishing them.
Climbing plants may be divided into four classes. First, those which twine spirally round a support, and are not aided by any other movement. Secondly, those endowed with irritable organs, which when they touch any object clasp it; such organs consisting of modified leaves, branches, or flower-peduncles. But these two classes sometimes graduate to a certain extent into one another. Plants of the third class ascend merely by the aid of hooks; and those of the fourth by rootlets; but as in neither class do the plants exhibit any special movements, they present little interest, and generally when I speak of climbing plants I refer to the two first great classes.
Twining Plants.
This is the largest subdivision, and is apparently the primordial and simplest condition of the class. My observations will be best given by taking a few special cases. When the shoot of a Hop (Humulus lupulus) rises from the ground, the two or three first-formed joints or internodes are straight and remain stationary; but the next-formed, whilst very young, may be seen to bend to one side and to travel slowly round towards all points of the compass, moving, like the hands of a watch, with the sun. The movement very soon acquires its full ordinary velocity. From seven observations made during August on shoots proceeding from a plant which had been cut down, and on another plant during April, the average rate during hot weather and during the day is 2 hrs. 8 m. for each revolution; and none of the revolutions varied much from this rate. The revolving movement continues as long as the plant continues to grow; but each separate internode, as it becomes old, ceases to move.
To ascertain more precisely what