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INTRODUCTION TO BOTANY 



of these ancient plants doubtless represented classes that are 

 extinct, and others were the older members or the ancestors 

 of the classes which we now have, which in some cases are 

 represented by only a few kinds of living plants. 



Most ferns grow in moist regions, but some species are found 

 in peculiarly dry situations, even growing like lichens on nearly 



FIG. 207. A group of maidenhair ferns 

 Photograph by W. H. P. Huber 



bare rocks. Although they show considerable variation in 

 form, they can in nearly all cases be distinguished from other 

 plants by their greatly divided, feather-like leaves (fig. 207). 

 Ferns have great range in size, from very small, lowly plants 

 to those as high as a man's head, and to the tropical tree ferns 

 that may be forty feet or more in height. They may occur 

 singly or in thickets so dense as to make it difficult to penetrate 

 them. In all except the tree ferns the parts of the plant that 

 we see are the leaves ; the stems and the roots are underground. 



