National Geographic : 1939 Aug
FLOWER PAGEANT OF THE MIDWEST The asters, goldenrods, and sunflowers all limit the work of each flower to the pro duction of one seed, and their great success seems to be due mostly to close co-opera tion among the florets of the flowerlike head. "ALL FOR ONE, ONE FOR ALL" As already suggested, the head is actu ally a socialized group in which each kind of floret or part has its own special task and in which waste is all but eliminated. In the dandelion, for example, the origi nal green calyx has become useless and is converted into a parachutelike device for air travel. Grass flowers have likewise taken on the social habit and have banded themselves together in small but efficient groups. However, the trees of our deciduous woods have lagged behind in their social organization, the catkins of pussy willow, birch, and oak having developed little feel ing for co-operation. At first thought, it appears strange that plants with brightly colored corolla should be the conservatives of the floral world and the grasses and trees with insignificant green flowers the progressives. This is quite at variance with man's interest in flowers, which often ignores the existence of flowers in grasses and our common shade trees. FLOWERS USE "COLOR ADVERTISING" Peas, asters, roses, and lilies, like nearly all other treasures of field and garden, have remained faithful to the practice of their buttercup ancestors, which were the first to turn to color advertising of their wares. This custom has been preserved by the large majority of flower families, though nearly all have improved upon it in one or more details. However, this adherence to tradition appears to have been more a matter of necessity than of choice, and attempts to break away from it have not been infre quent, the sunflower that became a hay fever ragweed being one of the innovators. Grasses and oaks have long lived in posi tions favorable to a change from the an cestral plan of pollen transport by insects, but the evidence indicates that their ex posure to wind was not the cause of their departure from accepted custom. This may well have been due to the advantage of having the first chance at power and raw materials, thus placing more food at their disposal. The consequence was to put emphasis upon the two parts, stamens and pistil, which are essential to seed production; less concern was taken for the corolla and this began slowly to disappear, the calyx fol lowing at a distance. Not a few plants, like the maples, are in the midst of this transformation today, and many still exhibit remnants of the once-useful corolla or calyx. Some, like the four-o'clock, flowering dogwood, and poinsettia, have pressed too rapidly along the path of progress, it seems, and have had to retrace their steps, calling in some other part, such as calyx or leaf, to act as substitute for the corolla. The final result was that all grasses came to be pollinated by the wind and now seem to show no relationship whatever to their remote forebears, the lilies. The oaks underwent similar changes from the pattern of the ancestral witch hazels and sumacs, but carried them to the further point of assigning stamens and pis tils to different flowers. AN AGE OF SPECIALIZATION There is considerable evidence that flowers are slowly changing today in the direction of further specialization. Much of this is due to the continuation of the processes just described, but some of it is to be assigned to the manifold disturbances wrought by man. Apart from the breaking by plow that has destroyed most of the prairie, these dis turbances include the alterations in cover and conditions due to grazing, and even more significant is the aftermath of change in abandoned fields and cutover wood lands. In spite of destruction and modification, there still remain many thousand square miles of fairly typical prairie, especially in the farther Middle West, and this may be much increased as the numerous projects for conservation are carried into effect. No important species of the prairie has vanished and few indeed of the rare ones, so that the local disappearance of favorites may be readily compensated for by plant ing in wild gardens, parks, reserves, and along highways. The guideposts for an excursion into Nature are placed here and there in the pages that follow.