CHAPTER XXV. 



FERNS. 



345. In taking up the study of the ferns we find plants which 

 are very beautiful objects of nature and thus have always attracted 

 the interest of those who love the beauties of nature. But they 

 are also very interesting to the student, because of certain re- 

 markable peculiarities of the structure of the fruit bodies, and 

 especially because of the intermediate position which they occupy 

 within the plant kingdom, representing in the two phases of 

 their development the primitive type of plant life on the one 

 hand, and on the other the modern type. We will begin our 

 study of the ferns by taking that form which is the more promi- 

 nent, the fern plant itself. 



346. The Christmas fern. One of the ferns which is very 

 common in the Northern States, and occurs in rocky banks and 

 woods, is the well-known Christmas fern (Aspidium acrostichoides) 

 shown in fig. 203. The leaves are the most prominent part of the 

 plant, as is the case with most if not all our native ferns. The 

 stem is very short and for the most part under the surface of the 

 ground, while the leaves arise very close together, and thus form 

 a rosette as they rise and gracefully bend outward. The leaf is 

 elongate and reminds one somewhat of a plume with the pinnae 

 extending in two rows on opposite sides of the midrib. These 

 pinnae alternate with one another, and at the base of each pinna 

 is a little spur which projects upward from the upper edge. 

 Such a leaf is said to be pinnate. While all the leaves have the 

 same general outline, we notice that certain ones, especially those 

 toward the center of the rosette, are much narrower from the 



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