Page:Popular Science Monthly Volume 25.djvu/352

340 common yellow ragwort, or in the daisy and the sunflower, have been flattened out into long rays, which serve as pennants or banners to catch the insect eye. They are very successful flowers, perhaps the most successful family on the whole earth. But the groundsel, for some reason of its own, has reversed the general family policy. It is rarely visited by insects, and has, therefore, apparently taken once more to self-fertilization; and a complete alteration has thus been effected in its appearance, when compared with its sister composites. Though it has not yet quite lost its yellow center blossoms, it has no rays, and its bells are almost concealed by its large and ugly green involucre. Altogether, we may say that groundsel is a composite far advanced on its way to a complete loss of the characteristic composite habits. It still receives the visits of a very few stray insects; but it does not lay itself out to court them, and it is, probably, gradually losing more and more of its winged clients from day to day. Thus we see that any flower which will benefit by insect-fertilization, whether it be a monocotyledon or a dicotyledon, high up or low down in either series, is almost sure to acquire brilliant petals; while, on the other hand, any flower which gives up the habit of relying upon insects is almost sure to lose or minimize its petals once more, and return to a state resembling in general type the catkins and grasses or the still lowlier self-fertilized types.

The same sort of conclusion is forced upon us if we look at the various organs in each flower which display the brilliant pigments. The petals are most commonly the seat of the attractive coloration, as in the dog-rose and the marsh-mallow. But in many other flowers, like the fuchsia, the calyx is also beautifully colored, so as to aid in the general display. In the tulips and other lilies, the crocus, the iris, and the daffodil, sepals and petals are all colored alike. In marvel-of-Peru and purple clematis, the petals are wholly wanting. In the common meadow-rue, it is the essential floral organs themselves which act as allurements; while, in the mesembryanthemums, the outer stamens become flattened and petal-like, so as to resemble the corolla of other flowers. In the composites, like daisies, where many blossoms are crowded on one head, the outer row of blossoms is often similarly flattened into rays which only serve the purpose of attracting insects toward the fertile flowers of the center. Nor does the coloring process stop at the regular parts of the flower alone: the neighboring bracts and leaves are often even more beautifully tinted than the flowers themselves. In the great white arums, grown in windows as Ethiopian lilies, the actual blossoms lie right inside the big sheath or spathe, and cluster round the tall yellow spike or spadix in the center: and this sheath acts the part of petals in the more ordinary flowers. Many euphorbias have very inconspicuous little blossoms, but each small colony is surrounded by a scarlet involucre which makes them some of the gayest among our hot-house plants. The poinsettia,