EQUISETACEAE. 



259 



of development Equisetaceae correspond closely with 

 Filices, but differ remarkably in the relative importance 

 of leaf and axis respectively in the two groups. In 

 Filices the leaves are the most conspicuous organs, in 



TlG- 902 



-Unbranched fertile, and branched barren, fronds of 

 Horsetail. 



some of our own species attaining a length of several 

 feet, while in Equisetaceae the leaves are reduced to the 

 toothed cylindrical sheaths which are found at every 

 joint of the conspicuous, simple or verticillately branched, 

 stem. In one species, the Scouring or Dutch Rush (J5. 

 hyemafy, the epidermis contains so much silica, that 

 bunches of the stem are sold for polishing metal. 



3. Natural Order Lycopodiaceae. The Club-moss 

 Family. 



Type Lesser Club-moss (Selaginella selaginoides). 



A slender, moss-like plant, growing in wet, stony situa- 

 tions, 2 to 4 inches high, with narrow, pointed leaves, 

 those on the erect fruiting branches bearing sporanges 

 of two kinds in their axils. 



There are six British species of Club-moss, and the 

 small species which we have selected as Type differs 

 from the rest in bearing two kinds of spores, on which 



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