DEVELOPMENT OF PLANTS 311 



The club moss ferns are a much -larger group than the Equise- 

 tales, but like the latter group, they are a remnant of a highly 

 developed and widely distributed race. Fossil remains indicate 

 that the ancient allies of these plants were conspicuous features 



Fig. 237. Cross-section of a portion of the stem of Ly cop odium, showing 

 the centrally arranged vascular bundles. 



of an earlier vegetation, with palm-like trunks 100 feet in height 

 and three feet in diameter, and bearing a crown of long narrow 

 leaves that attained a length of three feet. They reached their 

 greatest abundance in the coal age and thence gradually declined, 

 being crowded out by the more specialized seed plants. There 

 are two important families of the Lycopodiales : 1, Lycopodiaceae; 

 2, Selaginellaceae. 



116. Family 1. Lycopodiaceae. — With but one exception the 

 members of this family belong to the genus Lycopodium, com- 

 monly known as the club moss fern, ground or running pine or 

 ground fir, etc. (Fig. 236). These plants are very well repre- 

 sented in our open woods, where they often form conspicuous 

 colonies owing to the extensive branching and prolonged growth 

 of the stems which creep over or through the ground, sending 



