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Darwin, Charles, 1809-1882

"The Movements and Habits of Climbing Plants"

23 m. The stem is thin and flexible, and I have seen one make
four regular spiral turns round a thin upright stick, ascending of
course from right to left, and therefore in a reversed direction
compared with the before described species. Afterwards, from the
interference of the tendrils, it ascended either straight up the
stick or in an irregular spire. The tendrils are in some respects
highly remarkable. In a young plant they were about 2.5 inches in
length and much branched, the five chief branches apparently
representing two pairs of leaflets and a terminal one. Each branch
is, however, bifid or more commonly trifid towards the extremity,
with the points blunt yet distinctly hooked. A tendril bends to any
side which is lightly rubbed, and subsequently becomes straight
again; but a loop of thread weighing 0.25th of a grain produced no
effect. On two occasions the terminal branches became slightly
curved in 10 m. after they had touched a stick; and in 30 m. the tips
were curled quite round it. The basal part is less sensitive. The
tendrils revolved in an apparently capricious manner, sometimes very
slightly or not at all; at other times they described large regular
ellipses.


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