The walking fern has a most original way of getting over the ground. It bends its slender frond and starts a root by extending the tip of the mid-rib; so it sets up a new plant and is anchored fast on all sides by its rooted frond tips, covering the ground with a rich carpet of verdure. The variety of runners along the ground is as great as the climber. All motion of the plant is a form of growth. The plant grows by day and by night, but more by day, as light and heat are incentives to growth.
Interesting as is the study of plant motion, let us forsake it and consider for a little plant food. The plant receives food from earth, water, and air. The earth gives the plant sulphur, iron, soda, magnesia, phosphorus, and other mineral substances. These are all fed to the plant in a solution of water.
From the rain the plant receives as food hydrogen and forms of ammonia.
From air the plants absorb carbon, oxygen, nitrogen, and ammonia; very much of the first, little of the second, and very little of the others.
When plants grow out-of-doors, the winds, dews, and rains free the leaves from accumulations of dust which obstruct the pores and hinder the receiving of food. In very dry and dusty seasons we notice that the plants become sickly from the stopping of the pores. Plants need clean skins as human beings do.
House plants should be well washed all over now and then, to admit of their getting their proper amount of food from the air.
Certain classes of plants use a portion of animal food. We are accustomed to the idea of animals eating plants, but when we see the tables turned, and the plants eating animals, that is queer, indeed! The animal food of the “flesh-eating,” or carnivorous, plants is really the juice sucked from the bodies of insects.
The sun dew, common in marshes, expands a little, sticky, pink-green shirt-button of a leaf, on which are numerous stiff hairs. The clear drops of gum attract insects to the leaf, and they are held by the feet or wings. Their struggles cause the leaf to fold together, when the hairs pierce the body of the insect and drink up the juices. When only a dry husk remains the leaf opens and the wind shakes the shell away.
The pitcher-plant invites insects by a honey-like secretion. They fall into the liquid stored in the pitcher and are thus drowned, because, owing to numerous downward-pointing hairs in the throat of the pitcher, they cannot climb back. Easy is the descent into evil! The acrid liquid in the pitcher digests the bodies of the insects, turning them into plant food. Flies, ants, gnats, little beetles, are often caught, but bees very seldom. Bees have their own affairs to attend to, and cannot go picnicing into pitcher-plants.