But some plants produce roots in the air, as in poison ivy and the trumpet creeper, without injury or the gardener’s skill, and are known as aërial roots. They are some of the most peculiar and fantastic of nature’s devices for allowing plants to grow in apparently unfavorable places. In many orchids, some relatives of the pineapple, and a few other air-inhabiting plants, the roots live wholly in the air, the plants being fastened to a tree or even to a telegraph wire. Such plants live on the air and water vapor, and are mostly inhabitants of moist tropical regions.
In the East Indies and in Africa there is a pitcher plant—in fact, scores of varieties of them—which grows up on the branches of trees. In this case the pitcher may be as long as some of our American kinds, often twelve to eighteen inches, and many of them are attached to a slender leafstalk two to three feet long, by which they hang suspended. Insects, literally by the thousands, are caught in these gaudy traps, for many of the pitchers are beautifully colored, and near the opening they secrete a sweetish liquid that lures their prey. They are, in fact, such curious and handsome plants that they are commonly grown in greenhouse collections.