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
_Tropæolum minus_ (?).—The internodes of a variety named “dwarf crimson
Nasturtium” did not revolve, but moved in a rather irregular course
during the day to the light, and from the light at night. The petioles,
when well rubbed, showed no power of curving; nor could I see that they
ever clasped any neighbouring object. We have seen in this genus a
gradation from species such as _T. tricolorum_, which have extremely
sensitive petioles, and internodes which rapidly revolve and spirally
twine up a support, to other species such as _T. elegans_ and _T.
tuberosum_, the petioles of which are much less sensitive, and the
internodes of which have very feeble revolving powers and cannot spirally
twine round a support, to this last species, which has entirely lost or
never acquired these faculties. From the general character of the genus,
the loss of power seems the more probable alternative.
In the present species, in _T. elegans_, and probably in others, the
flower-peduncle, as soon as the seed-capsule begins to swell,
spontaneously bends abruptly downwards and becomes somewhat convoluted.
If a stick stands in the way, it is to a certain extent clasped; but, as
far as I have been able to observe, this clasping movement is independent
of the stimulus from contact.
ANTIRRHINEÆ.—In this tribe (Lindley) of the Scrophulariaceæ, at least
four of the seven included genera have leaf-climbing species.
_Maurandia Barclayana_.—A thin, slightly bowed shoot made two
revolutions, following the sun, each in 3 hrs. 17 min.; on the previous
day this same shoot revolved in an opposite direction. The shoots do not
twine spirally, but climb excellently by the aid of their young and
sensitive petioles. These petioles, when lightly rubbed, move after a
considerable interval of time, and subsequently become straight again. A
loop of thread weighing ⅛th of a grain caused them to bend.
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