the power of climbing as an adaptation by means of which plants are
enabled to reach the light. Instead of being compelled 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 reached." ("Climbing
Plants" (2nd edition 1875), page 193.)

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 LEAF-CLIMBERS, which may be looked
on as incipient tendril-bearers, occurring in the same genera with
simple twiners. (Loc. cit. page 195.) 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 remarkable
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 (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 s