Climbing Plants 387 
His work on climbing plants was his first sustained piece of work 
on the physiology of movement, and he remarks in 1864: “This has 
been new sort of work for me.” He goes on to remark with some- 
thing of surprise, “I have been pleased to find what a capital guide 
for observations a full conviction of the change of species is.” 
It was this point of view that enabled him to develop a broad 
conception of the power of climbing as an adaptation by means of 
which plants are enabled to reach the light. Instead of being com- 
pelled to construct a stem of sufficient strength to stand alone, they 
succeed in the struggle by making use of other plants as supports. 
He showed that the great class of tendril- and root-climbers which 
do not depend on twining round a pole, like a scarlet-runner, but 
on attaching themselves as they grow upwards, effect an economy. 
Thus a Phaseolus has to manufacture a stem three feet in length to 
reach a height of two feet above the ground, whereas a pea “which 
had ascended to the same height by the aid of its tendrils, was but 
little longer than the height reached2.” 
Thus he was led on to the belief that twining is the more ancient 
form of climbing, and that tendril-climbers have been developed 
from twiners. In accordance with this view we find leafclimbers, 
which may be looked on as incipient tendril-bearers, occurring in 
the same genera with simple twiners®. He called attention to the 
case of Maurandia semperflorens in which the young flower-stalks 
revolve spontaneously and are sensitive to a touch, but neither 
of these qualities is of any perceptible value to the species. This 
forced him to believe that in other young plants the rudiments of 
the faculty needed for twining would be found—a prophecy which 
he made good in his Power of Movement many years later. 
In Climbing Plants he did little more than point out the remark- 
able fact that the habit of climbing is widely scattered through the 
vegetable kingdom. Thus climbers are to be found in 35 out of the 
59 Phanerogamic Alliances of Lindley, so that “the conclusion is 
forced on our minds that the capacity of revolving’, on which most 
1 Life and Letters, 10. p. 315. He had, however, made a beginning on the movements 
of Drosera. 
2 Climbing Plants (2nd edit. 1875), p. 193. 
3 Loe. cit. p. 195. 
4 If a twining plant, e.g. a hop, is observed before it has begun to ascend a pole, it will 
be noticed that, owing to the curvature of the stem, the tip is not vertical but hangs over 
in a roughly horizontal position. If such a shoot is watched it will be found that if, for 
instance, it points to the north at a given hour, it will be found after a short interval 
pointing north-east, then east, and after about two hours it will once more be looking 
northward. The curvature of the stem depends on one side growing quicker than the 
opposite side, and the revolving movement, i.e. circumnutation, depends on the region of 
quickest growth creeping gradually round the stem from south through west to south 
again. Other plants, e.g. Phaseolus, revolve in the opposite direction. 
25—2 
