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Darwin, Charles, 1809-1882

"The Movements and Habits of Climbing Plants"

--Cardiospermum halicacabum.--In this family, as in the
last, the tendrils are modified flower-peduncles. In the present
plant the two lateral branches of the main flower-peduncle have been
converted into a pair of tendrils, corresponding with the single
"flower-tendril" of the common vine. The main peduncle is thin,
stiff, and from 3 to 4.5 inches in length. Near the summit, above
two little bracts, it divides into three branches. The middle one
divides and re-divides, and bears the flowers; ultimately it grows
half as long again as the two other modified branches. These latter
are the tendrils; they are at first thicker and longer than the
middle branch, but never become more than an inch in length. They
taper to a point and are flattened, with the lower clasping surface
destitute of hairs. At first they project straight up; but soon
diverging, spontaneously curl downwards so as to become symmetrically
and elegantly hooked, as represented in the diagram. They are now,
whilst the flower-buds are still small, ready for action.
The two or three upper internodes, whilst young, steadily revolve;
those on one plant made two circles, against the course of the sun,
in 3 hrs.


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