Ferns : Habitats, Life-Story, Morphology 



fern-plant as the offspring, it will help us to understand 

 what botanists mean when they say that ferns exhibit in 

 their lives the phenomenon known as "alternation of 

 generations." The prothallium they call the sexual 

 generation, because it bears the male and female organs 

 of the plant, and what we call the fern-plant botanists 

 look upon merely as the spore-bearing generation in 

 the life of a fern. Now, if we think of the prothallium 

 giving birth to the spore-bearing generation, and of the 

 spore-bearing generation producing new prothallia, 

 which in turn give rise to a later spore-bearing genera- 

 tion, we see what is meant by saying the generations 

 alternate with each other. 



Having now learned something of the life-history of 

 ferns, we must study for a little the fully-grown or 

 adult fern. All ferns in the adult state possess roots, 

 stems, and leaves. The roots are always fibrous 

 (threadlike), and must be carefully distinguished from 

 the stems which creep under, and sometimes above, the 

 surface of the soil. These creeping stems, some of 

 which attain to a considerable degree of thickness, are 

 called " rootstocks," or "rhizomes." From the rhi- 

 zomes the true roots grow downwards and the leaves 

 upward. The leaves are sometimes arranged alter- 

 nately on opposite sides of the rhizome, but at other 

 times they are grouped in tufts or circles round its 

 growing tip. Fronds possessing the former arrange- 

 ment with regard to leaves may be said to have the 

 power of locomotion and may be truly called " walking 

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