Aylin Lehmann Beginner
  • Member since Dec 3rd 2018
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Posts by Aylin Lehmann

    In some plants this is accomplished by the anthers being just above the stigma, and when the pollen is ripe and the ovule ready, the stigma is found to be covered with a sticky substance. As the falling pollen grains touch the stigma, they are caught in this sticky substance just as surely as flies are caught once they touch a fly paper. But just here one of the most wonderful processes of nature begins. The pollen grain begins, slowly at first, to grow, and in the act it penetrates the outer coat of the stigma with a minute pollen tube.

    This slender threadlike tube, carrying with it the male germ, grows straight down through the stigma, into the narrowed style, and through this to the ovule. Once the pollen is caught on the stigma, nothing is so sure of fulfillment as that this male fertilizing stuff will ultimately reach the ovule. For the hitherto virgin ovule this impregnation starts a new phase in life. It means the beginning of the end, but in the process fruit and seed will be developed, and the young bride, already a mother, has triumphantly accomplished that for which she exists.

    Nature sometimes finds still other ways of using strange and curious-shaped leaves, and in our American bogs is a group of plants, also insect digesters, still more unusual than the pitcher plants. In bright sunny places in open bogs one may often find small reddish, glistening plants, called sundews, usually only a few inches tall, covered with sticky hairs. In fact, the glistening is due to the secretion of the sticky substance, a tiny drop of which may be found at the end of each hair. Flying insects are caught in these leaves, and, as a fly on fly paper, the greater the struggle the more involved does the insect become among the sticky threads. Once caught by such a plant, escape is practically impossible.

    The occurrence of organic acids, or their derivatives, which have pronounced odors or flavors, in the flesh surrounding the seeds of fruits, in the endosperm of vegetable seeds, or in the tubers, etc., of perennial plants, thus making them attractive as food for animals and men, undoubtedly serves to insure a wider distribution of the reproductive organs of these plants; a fact which has unquestionably had a marked influence upon the survival of species in the competitive struggle for existence during past eras and in the development and cultivation of different species by man. Indirect evidence that the proportion of these attractive compounds present in certain species may have been considerably increased by the processes of "natural selection" in the past is furnished by the many successful attempts to increase the percentage of such desirable constituents in fruits or vegetables by means of artificial selection of parent stocks by skillful plant breeders.