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Darwin, Charles, 1809-1882

"The Movements and Habits of Climbing Plants"

The tendrils of a plant which had crawled over a large
box-tree clasped several of the branches; but I have repeatedly seen
that they will withdraw themselves after seizing a stick. When they
meet with a flat surface of wood or a wall (and this is evidently
what they are adapted for), they turn all their branches towards it,
and, spreading them widely apart, bring their hooked tips laterally
into contact with it. In effecting this, the several branches, after
touching the surface, often rise up, place themselves in a new
position, and again come down into contact with it.
In the course of about two days after a tendril has arranged its
branches so as to press on any surface, the curved tips swell, become
bright red, and form on their under-sides the well-known little discs
or cushions with which they adhere firmly. In one case the tips were
slightly swollen in 38 hrs. after coming into contact with a brick;
in another case they were considerably swollen in 48 hrs., and in an
additional 24 hrs. were firmly attached to a smooth board; and
lastly, the tips of a younger tendril not only swelled but became
attached to a stuccoed wall in 42 hrs. These adhesive discs
resemble, except in colour and in being larger, those of Bignonia
capreolata.


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