But, during the endless fluctuations of the
conditions of life to which all organic beings have been exposed, it
might be expected that some climbing plants would have lost the habit
of climbing. In the cases given of certain South African plants
belonging to great twining families, which in their native country
never twine, but reassume this habit when cultivated in England, we
have a case in point. In the leaf-climbing Clematis flammula, and in
the tendril-bearing Vine, we see no loss in the power of climbing,
but only a remnant of the revolving power which is indispensable to
all twiners, and is so common as well as so advantageous to most
climbers. In Tecoma radicans, one of the Bignoniaceae, we see a last
and doubtful trace of the power of revolving.
With respect to the abortion of tendrils, certain cultivated
varieties of Cucurbita pepo have, according to Naudin, {47} either
quite lost these organs or bear semi-monstrous representatives of
them. In my limited experience, I have met with only one apparent
instance of their natural suppression, namely, in the common bean.
All the other species of Vicia, I believe, bear tendrils; but the
bean is stiff enough to support its own stem, and in this species, at
the end of the petiole, where, according to analogy, a tendril ought
to have existed, a small pointed filament projects, about a third of
an inch in length, and which is probably the rudiment of a tendril.
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