Two
vigorous young plants of N. laevis and N. distillatoria, in my
hothouse, whilst less than a foot in height, showed no sensitiveness
in their leaves, and had no power of climbing. But when N. laevis
had grown to a height of 16 inches, there were signs of these powers.
The young leaves when first formed stand upright, but soon become
inclined; at this period they terminate in a stalk or filament, with
the pitcher at the extremity hardly at all developed. The leaves now
exhibited slight spontaneous movements; and when the terminal
filaments came into contact with a stick, they slowly bent round and
firmly seized it. But owing to the subsequent growth of the leaf,
this filament became after a time quite slack, though still remaining
firmly coiled round the stick. Hence it would appear that the chief
use of the coiling, at least whilst the plant is young, is to support
the pitcher with its load of secreted fluid.
Summary on Leaf-climbers.--Plants belonging to eight families are
known to have clasping petioles, and plants belonging to four
families climb by the tips of their leaves. In all the species
observed by me, with one exception, the young internodes revolve more
or less regularly, in some cases as regularly as those of a twining
plant.
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