How Plants Climb

Pacific Press Publishing Association · Mountain View, California · Oct 3, 1911

FromSigns of the Times, Vol. 38, No. 39.

THE slender and apparently insignificant tendrils of the climbing plant exhibit movements that show the possession of instinct; at least, similar movements among the lower animals would be ascribed to instinct or to reason.

The general characteristics of tendril climbers may be best understood by citing the actions of one of the common climbers in the fields or the gardens—for example, the wild cucumber, known to botanists as Echinocystis lobata.

This climbing herb has large, three-lobed leaves, and opposite the leaves are slender, three-parted tendrils, seven to nine inches long. These tendrils are the arms by which the plant is to cling to its support. They begin to revolve before they are full-grown in search for a support on which to cling. Moreover, the upper two or three joints of the vine also revolve in little circles a few inches in diameter. This revolving of the stem causes the tendrils to sweep in a wider circle.

The circle swept by the tendrils is fifteen or sixteen inches in diameter, and it is completed in about an hour and a half. The tendril must, therefore, travel a little over an inch in two minutes. The tendrils revolve in such a manner that they must strike the main stem of the plant and be arrested were there not some provision for avoiding it. When the tendril in its revolution has nearly reached the stem it bends upward until the stem is passed, and then falls down to its original position.

This movement it repeats with accuracy in every revolution. The tendril revolves in a nearly horizontal plane. If the vine should be thrown to the ground, so that the tendrils should hang downward, they suddenly cease to revolve, and begin to bend themselves upward. When they have reached a horizontal position they begin to revolve again.

The tip of the tendril is slightly hooked, and the concave surface of the hook is highly sensitive to touch. As soon as this surface strikes a stick, the tendril begins to coil and to draw the plant up to the stick. This tendril may be readily deceived, for if we touch the concave surface ever so lightly with the finger it will begin to curve sensibly in one or two minutes. If the touch is rough, the tendril will, after a time, coil up into a complete spiral, and its motion will cease. The tendril will eventually discover its mistake, however, and will uncoil and begin again to revolve.

One of the peculiarities to be noticed in connection with the twining of plants is the fact that with very few exceptions all the individuals of one species always twine in the same direction. Most plants twine in an opposite course to the movement of the sun or the hands of a watch. Such twiners are the morning-glory, wistaria, wax-plant, trumpet-creeper, and many others. Among those which twine in the opposite direction the hop and wild bindweed, or climbing polygonum, are familiar examples.—Harper's Weekly.