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Darwin, Charles, 1809-1882

"The Movements and Habits of Climbing Plants"

If it has merely adapted itself to the inequalities of a
thick post, though it has clasped nothing, or if it has inserted its
apex into some little fissure, this stimulus suffices to induce
spiral contraction; but the contraction always draws the tendril away
from the post. So that in every case these movements, which seem so
nicely adapted for some purpose, were useless. On one occasion,
however, the tip became permanently jammed into a narrow fissure. I
fully expected, from the analogy of B. capreolata and B. littoralis,
that the tips would have been developed into adhesive discs; but I
could never detect even a trace of this process. There is therefore
at present something unintelligible about the habits of this plant.
Bignonia picta.--This species closely resembles the last in the
structure and movements of its tendrils. I also casually examined a
fine growing plant of the allied B. Lindleyi, and this apparently
behaved in all respects in the same manner.
Bignonia capreolata.--We now come to a species having tendrils of a
different type; but first for the internodes. A young shoot made
three large revolutions, following the sun, at an average rate of 2
hrs.


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