A valuable oil is expressed from the seeds of the opium poppy. This oil is used for illuminating purposes in some parts of the world, and also for soap-making. The finer quality is used as food, instead of olive oil, in countries where oil is eaten instead of butter, and it is also used in grinding artists’ colors. OTHER SEEDS THAT ARE MOVED BY THE WIND. [Illustration] Many, many other plants have seeds or seed pods that can be carried away by the wind. The fields and hedges are full of plumes and winged seeds, and of seeds so light as to be readily carried away without special plumes or wings. At the top of this page is the picture of a trumpet vine. When you have the chance, examine the seeds in the pod of the trumpet vine and see how they are enabled to fly away. Hops are pretty plants, and useful ones as well, and if you examine hop seeds—you will see—what you will see! Some clovers have seeds that fly. See if you can find them. [Illustration] Linden trees are covered with clusters of white sweet-scented flowers in the early summer. Each cluster of flowers is attached in a curious way to a wing, and often the whole cluster, with its wing, falls together and is blown to some distance by the wind. When the lindens are in bloom you will know it by the humming of the bees, for they are very fond of linden honey, and the trees often sound like an enormous beehive, there are so many bees about them. It would take altogether too long to tell about all the seeds that are carried by the wind, but you can find a great many of them without being told; and that, after all, is the best way. At the bottom of this page are the seed pods of the cow parsnip, a very large, coarse, but rather handsome weed, often found in the corners of pastures. You can see that its seed pods fly. TUMBLEWEEDS. Tumbleweeds _are_ funny! They do not fly in the air, but they go scurrying over the surface of the earth. They grow on the Western plains and in other places, and sometimes get to be as large as a bushel basket. [Illustration] They are not very interesting until they begin to tumble. This happens in the fall of the year. The plants grow like ordinary little bushes in the summer and bear a great many clusters of small flowers. Late in the season the leaves fall off, and the stems of the plant curl over and make a ball of it. The seeds do not fall yet; they can be seen in pretty brown clusters inside the ball. Along comes a gust of wind; the tumbleweed, all rolled up and quite dry now, breaks loose from the earth and away it goes, head over heels, rolling like a wild thing across the prairies. It is very funny to see a prairie full of tumbleweeds racing along. They look as if they were playing tag. When a train passes, those near the track are caught in the draught and off they start, head over heels, as fast as they can. They look exactly as if they were chasing the train.