When, however, they have
once completely clasped a stick, if this is removed, they do not
straighten themselves. The most remarkable fact, and one which I
have observed in no other species of the genus, is that the filaments
and the petioles of the young leaves, if they catch no object, after
standing for some days in their original position, spontaneously and
slowly oscillate a little from side to side, and then move towards
the stem and clasp it. They likewise often become, after a time, in
some degree spirally contracted. They therefore fully deserve to be
called tendrils, as they are used for climbing, are sensitive to a
touch, move spontaneously, and ultimately contract into a spire,
though an imperfect one. The present species would have been classed
amongst the tendril-bearers, had not these characters been confined
to early youth. During maturity it is a true leaf-climber.
Tropaeolum azureum.--An upper internode made four revolutions,
following the sun, at an average rate of 1 hr. 47 m. The stem twined
spirally round a support in the same irregular manner as that of the
last species. Rudimentary leaves or filaments do not exist. The
petioles of the young leaves are very sensitive: a single light rub
with a twig caused one to move perceptibly in 5 m.
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