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Darwin, Charles, 1809-1882

"The Movements and Habits of Climbing Plants"

The tendrils on a fine plant were eleven inches long, with
the petiole bearing two pairs of leaflets, only two and a half inches
in length. They revolve more rapidly and vigorously than those of
any other tendril-bearer observed by me, with the exception of one
kind of Passiflora. Three large, nearly circular sweeps, directed
against the sun were completed, each in 1 hr. 15 m.; and two other
circles in 1 hr. 20 m. and 1 hr. 23 m. Sometimes a tendril travels
in a much inclined position, and sometimes nearly upright. The lower
part moves but little and the petiole not at all; nor do the
internodes revolve; so that here we have the tendril alone moving.
On the other hand, with most of the species of Bignonia and the
Eccremocarpus, the internodes, tendrils, and petioles all revolved.
The long, straight, tapering main stem of the tendril of the Cobaea
bears alternate branches; and each branch is several times divided,
with the finer branches as thin as very thin bristles and extremely
flexible, so that they are blown about by a breath of air; yet they
are strong and highly elastic. The extremity of each branch is a
little flattened, and terminates in a minute double (though sometimes
single) hook, formed of a hard, translucent, woody substance, and as
sharp as the finest needle.


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