The Movements and Habits of Climbing PlantsDarwin, Charles
Science
The Movements and Habits of Climbing Plants
Darwin, Charles
Climbing plants; Geotropism; Plants; Plants -- Irritability and movements
_Lathyrus aphaca_.—This plant is destitute of leaves, except during a
very early age, these being replaced by tendrils, and the leaves
themselves by large stipules. It might therefore have been expected that
the tendrils would have been highly organized, but this is not so. They
are moderately long, thin, and unbranched, with their tips slightly
curved. Whilst young they are sensitive on all sides, but chiefly on the
concave side of the extremity. They have no spontaneous revolving power,
but are at first inclined upwards at an angle of about 45°, then move
into a horizontal position, and ultimately bend downwards. The young
internodes, on the other hand, revolve in ellipses, and carry with them
the tendrils. Two ellipses were completed, each in nearly 5 hrs.; their
longer axes were directed at about an angle of 45° to the axis of the
previously made ellipse.
_Lathyrus grandiflorus_.—The plants observed were young and not growing
vigorously, yet sufficiently so, I think, for my observations to be
trusted. If so, we have the rare case of neither internodes nor tendrils
revolving. The tendrils of vigorous plants are above 4 inches in length,
and are often twice divided into three branches; the tips are curved and
are sensitive on their concave sides; the lower part of the central stem
is hardly at all sensitive. Hence this plant appears to climb simply by
its tendrils being brought, through the growth of the stem, or more
efficiently by the wind, into contact with surrounding objects, which
they then clasp. I may add that the tendrils, or the internodes, or
both, of _Vicia sativa_ revolve.
COMPOSITÆ.—_Mutisia clematis_.—The immense family of the Compositæ is
well known to include very few climbing plants. We have seen in the
Table in the first chapter that _Mikania scandens_ is a regular twiner,
and F. Müller informs me that in S. Brazil there is another species which
is a leaf-climber. _Mutisia_ is the only genus in the family, as far as
I can learn, which bears tendrils: it is therefore interesting to find
that these, though rather less metamorphosed from their primordial foliar
condition than are most other tendrils, yet display all the ordinary
characteristic movements, both those that are spontaneous and those which
are excited by contact.
The long leaf bears seven or eight alternate leaflets, and terminates in
a tendril which, in a plant of considerable size, was 5 inches in length.
It consists generally of three branches; and these, although much
elongated, evidently represent the petioles and midribs of three
leaflets; for they closely resemble the same parts in an ordinary leaf,
in being rectangular on the upper surface, furrowed, and edged with
green. Moreover, the green edging of the tendrils of young plants
sometimes expands into a narrow lamina or blade. Each branch is curved a
little downwards, and is slightly hooked at the extremity.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account