Groups into Which Plants Naturally Fall 457 



out beyond their own particular situation. They exhibit three 

 main divisions. First are the true Ferns, whose gracefully-cut 

 fronds and general habit of life are too familiar to need any de- 

 scription, though the reader should remember that in the tropics 

 they grow into trees, among the most beautiful, though not the 

 largest, that there are. Second are the Horsetails, which are stiff, 

 green, rush-like plants, with terminal spore-cones, distinguished 

 from the true rushes by their little leaf scales. They are no taller 

 than two or three feet, and grow mostly in shoal water, or wet 

 places, but sometimes on open sandy banks. Third are the Club- 

 mosses, creeping, leafy, and not unlike their namesakes, the true 

 Mosses, but much coarser, as the conmion Ground Pine well 

 illustrates, or the decorative Selaginella of our greenhouses ; while 

 they are further distinguished by their little terminal cone-like 

 masses of spore cases. In size all three divisions of the Fern- 

 plants are now greatly degenerate from a former high estate, for, 

 along with others now extinct, they once grew into the trees promi- 

 nent in the earlier geological periods. In color all are green from 

 the chlorophyll with which they make their own food, and no 

 other color occurs, save an occasional red blush in young leaves, 

 and the brown of their spore-cases or stems. Their cellular anat- 

 omy is well differentiated into tissues of different functions, in- 

 cluding a highly-efficient system of water-carrying ducts to- 

 gether with strengthening fibers ; and it was the possession of this 

 fibrovascular system, no doubt, which permitted these plants to 

 carry their foliage high above earth upon lofty stems from deeply- 

 anchored roots, thus giving the world its first forests. Their 

 reproduction is by spores spread afar by the wind from the up- 

 right plant, and this spore-formation alternates with fertilization 

 which occurs in a way and a place not suspected by most persons. 

 Thus in the true Ferns, and the process is substantially the same 

 in principle in the Horsetails and Club-mosses, the little brown 

 spores from the under sides of the fronds do not grow into plants 

 like those which produce them, but into small (a quarter-inch in 



