Page:Popular Science Monthly Volume 45.djvu/31

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over is evidently tending strongly to a more perfect diœcism When it finishes its task of eliminating the filaments as it has the anthers of the stamens in many of the pistillate blossoms, and gets rid of the superfluous pistils of the staminate blossoms, it will accomplish its purposes of reproduction with less waste than at present.

A plant in the condition of the arbutus may be said to be in a certain sense at a "parting of the ways." To attain the end of cross-fertilization—the carrying of the pollen from the stamens of one plant to the pistils of another—two methods appear to be open to it. It may, and in the case of many of the Blueberry Hill specimens evidently has, become more perfectly diœcious by aborting the stamens on some plants and the pistils on others; or it might become dimorphous by developing perfect sexual organs

PSM V45 D031 Variations of the mayflower.jpg
Fig. 2.—Variations of the Mayflower.

in each blossom and having them at different heights—that is, having the stamens in one plant reach the mouth of the corolla and the pistil reach only half way to the mouth, while in another having the pistil long and the stamens short. The tendency toward dimorphism or trimorphism is shown by the varying lengths of the styles and filaments.

The blossoms of the common asparagus of our gardens show by their structure that they are in a transition stage somewhat similar to that of the arbutus. The staminate blossoms have rudimentary pistils and the pistillate blossoms rudimentary stamens, and sometimes a blossom is found which has both sets of organs in good condition—a reversion to an earlier condition of the plant.

The partridge berry,[1] a plant which has to contend with much the same external conditions as the arbutus, living in similar situations and remaining close to the ground, has adopted

  1. Mitchella repens.