The Mystery of Sex, or Sex Polarity

...of contractility the capacity for parts of a plant to shrink, move, or close when touched or stimulated. This is the case with the stigma of the tulip and one variety of the sensitive plant; in these plants, this movement is observed to occur not only after the application of the pollen to the stigma, but also when excited by any other means of stimulation.

The flowers of some plants, during and after fertilization original: "fecundation", also show an increase in heat; in some cases, this is so marked that it can be easily detected with a thermometer. This is said to be especially true of the Italian Arum original: "arum of Italy," a plant known for its "heat-generating" flowers. In some plants where the pistil is longer than the stamens—thereby raising the stigma above the anthers—the female organ is often observed to bend over and lower itself so that it can come within reach of the anthers.

Fertilization of the female elements by the pollen of the male element in plant life is achieved in numerous and various ways. In instances where the male and female organs are located on different plants, as in the case of willows and others, the pollen is carried to the female flower by passing breezes; this transfer is often achieved over great distances. But the more frequent method, and the one used when the male and female elements are near each other, is fertilization by means of insects, small birds, and even small animals like the snail.

Sprengel Christian Konrad Sprengel (1750–1816) was a German botanist who was a pioneer in studying how flowers are fertilized by insects. was one of the first naturalists to discover and announce this "secret of nature." He anticipated the later research of Darwin and indeed cleared a path for that later scientist. As Geddes Patrick Geddes (1854–1932), a biologist and author known for writing about the evolution of sex. says:

"Sprengel laid sure foundations, which are now somewhat hidden by the advanced theories original: "superstructures" that Darwin and others have built. To Sprengel's eyes, the many ways in which the nectar is protected from rain seemed full of 'intention.' He recognized in the markings of the petals brightly lit signposts original: "illumined finger-posts" designed to lead insects to the hidden stores; and he further demonstrated that in some bisexual flowers, it was physically impossible for the pollen from the stamens to pass to the tips of the carpels the female reproductive parts of the flower. His general conclusion, freely stated, was that 'since a large number of flowers have separate sexes, and probably at least as many hermaphrodites organisms having both male and female sex organs have the stamens and carpels ripening at different times, nature appears to have designed that no flower shall be...'"