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Darwin, Charles, 1809-1882

"The Movements and Habits of Climbing Plants"

By these
combined movements of the young internodes, petioles, and tendrils, a
considerable space is swept in search of a support.
In young plants the tendrils are about three inches in length: they
bear two lateral and two terminal branches; and each branch
bifurcates twice, with the tips terminating in blunt double hooks,
having both points directed to the same side. All the branches are
sensitive on all sides; and after being lightly rubbed, or after
coming into contact with a stick, bend in about 10 m. One which had
become curved in 10 m. after a light rub, continued bending for
between 3 hrs. and 4 hrs., and became straight again in 8 hrs. or 9
hrs. Tendrils, which have caught nothing, ultimately contract into
an irregular spire, as they likewise do, only much more quickly,
after clasping a support. In both cases the main petiole bearing the
leaflets, which is at first straight and inclined a little upwards,
moves downwards, with the middle part bent abruptly into a right
angle; but this is seen in E. miniatus more plainly than in E.
scaber. The tendrils in this genus act in some respects like those
of Bignonia capreolata; but the whole does not move from the light,
nor do the hooked tips become enlarged into cellular discs.


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