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BOTANY 



others the veins bear the spore cases, while in some ferns the 

 entire leaf is modified into a spore-bearing organ. 



The Horsetails. — This comprises a small group of plants, recognized by 

 their erect habit of growth, the leaves coming out in whorls on the stem. 



In most forms the stem contains considerable 

 silica. This gave to the plant its former use- 

 ful place in the household and its name of 

 the scouring rush. If you burn one of these 

 plants very carefully on a tin plate over a 

 very hot fire, the delicate skeleton of silica 

 may be seen. The horsetails, or Equisetums, 

 were once a very important part of the earth's 

 vegetation. Before the coal fields were formed 

 the ancestors of these plants flourished as 

 trees. A large amount of the coal of this 

 country is undoubtedly formed from the 

 trunks of the Equisetums of the Carboniferous 

 age. At present they are represented by a 

 very few species, none of which are over four 

 or five feet in height. 



Club Mosses. — Another relative of the 

 fern is the club moss {Lyco'podium) . It is 

 familiar to us as a Christmas decoration under 

 the name of ground pine. It is chiefly of 

 interest now as the representative of another 

 group of plants that flourished during the 

 Carboniferous age. 



Economic Value of Ferns. — It maybe 

 said that the ferns as a group have formed a 

 large part of the enormous deposits of almost 

 pure carbon that we call coal, from which we 

 now derive the energy to run our many en- 

 gines. 



Bryophytes 



An eqmsetum, about one half 

 natural size. 



Mosses, like ferns, are shade-loving 

 and moisture-loving plants. They form 

 velvety carpets in many of our forests, 

 but they often show their preference for moist localities by cover- 

 ing the wooded shores of lakes and swamps. 



Pigeon-wheat Moss. — One of the mosses frequently seen and 

 easily recognized is the so-called pigeon-wheat moss {Polytrichum 



