After their development the
tendrils contract spirally, and become woody and very strong. A
tendril in this state supported nearly seven ounces, and would
apparently have supported a considerably greater weight, had not the
fibres of flax to which the discs were attached yielded.
From the facts now given, we may infer that though the tendrils of
this Bignonia can occasionally adhere to smooth cylindrical sticks
and often to rugged bark, yet that they are specially adapted to
climb trees clothed with lichens, mosses, or other such productions;
and I hear from Professor Asa Gray that the Polypodium incanum
abounds on the forest-trees in the districts of North America where
this species of Bignonia grows. Finally, I may remark how singular a
fact it is that a leaf should be metamorphosed into a branched organ
which turns from the light, and which can by its extremities either
crawl like roots into crevices, or seize hold of minute projecting
points, these extremities afterwards forming cellular outgrowths
which secrete an adhesive cement, and then envelop by their continued
growth the finest fibres.
Eccremocarpus scaber (Bignoniaceae).--Plants, though growing pretty
well in my green-house, showed no spontaneous movements in their
shoots or tendrils; but when removed to the hot-house, the young
internodes revolved at rates varying from 3 hrs.
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