It may be said that many other plants will do this, but that is a mistake. Many flowers and leaves close at night and open in the day-time, but very few indeed exhibit the peculiar action of the sensitive plant in this respect. That plant will open at night if you bring a bright light into the room where it is growing, and it will close its leaves if the room is made dark in the day-time.
Other plants take note of times and seasons. The sensitive plant obeys no regular rules of this kind, but acts according to circumstances.
When I was a boy, I often used to go to a green-house where there were a great many beautiful and rare plants; but I always thought that the sensitive plant was the most wonderful thing in the whole collection, and I did not know then how susceptible it was to the influence of light. I was interested in it simply because it seemed to have a sort of vegetable reason, and understood that it should shut up its leaves whenever I touched it.
THE SENSITIVE PLANT.
But there were things around me in the vegetable kingdom which were still more wonderful than that, and I took no notice of them at all.
In the garden and around the house, growing everywhere, in the most common and ordinary places, were vines of various kinds—I think there were more morning-glories than anything else—and these exhibited a great deal more sense, and a much nearer approach to reasoning powers, than the sensitive plants, which were so carefully kept in the green-house.
When one of these vines came up out of the earth, fresh from its seed, the first thing it wanted, after its tendrils began to show themselves, was something to climb up upon. It would like a good high pole. Now, if there was such a pole within a few feet of the little vine it would grow straight towards it, and climb up it!
It would not grow first in one direction, and then in another and then in another, until it ran against something to climb on, but it would go right straight towards the pole, as if it saw it, and knew it was a good one for its purpose.