Page:Popular Science Monthly Volume 67.djvu/184

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By Professor W. J. BEAL,


Plants Protected by Growing under Thorn Bushes and Thistles.—C. G. Pringle, for many years a famous plant collector, especially in Mexico and the arid regions of the United States, speaks of a native grass of northern Mexico, Muhlenbergia Texana, as such a great favorite with all grazing animals that it is usually exterminated or nearly so, except when growing under the protection of thorny shrubs, usually mesquite bushes. In Arizona during the winter and spring, the Indians bring it long distances into the towns to sell. He adds, 'How many times I have contended with the horrid mesquite bushes to gather an armful of this grass to carry joyfully to my hungry and jaded horses.' In such cases the thorns, spines and perhaps bitter taste of the bushes not only protect the young growth and leaves of certain plants, but furnish shelter for other tender and nutritious herbage.

In arid regions, especially, similar instances of protection by thorn bushes are numerous.

Plants retire beneath the Surface of the Ground and are protected from Animals.—At the close of the growing season, large numbers of plants, especially in regions subject to protracted droughts or to severe cold, cast off their leaves, take on a condensed form and remain secure beneath the surface of the ground for months at a time in the form of bulbs, tubers and rootstocks. At such times they are nearly sure to escape destruction by animals. I only need to mention as examples Solomon's seal, Dutchman's breeches, May apple, goldenrod, artichoke.

Plants Protected from Animals by Water.—Not only the flowers of many species of plants as they project above the surface of the water are protected from most unwelcome insects, but the whole plants as well.

Mud turtles, certain fishes, water snails, larvae of insects, eat aquatic plants, but most other animals are unable to reach them in such places.

Water-plantain, wild rice, pond lilies, arrow-head, pickerel-weed, pondweed, lizard's tail, bulrush, bur-reed, cat-tail flag, water dock, and many more of their associates, root at the bottom with leaves floating on the surface or projecting above.

Innumerable low forms, known as algae, are at home in lakes, ponds and streams or on the surface of the water, while other kinds thrive in salt or brackish water. These aquatics find protection below