CALAMITES AND LYCOPODS 



377 



prefer a substratum rich in humus or other organic matter. 

 Most of the species are restricted to one hemisphere, but 

 a few occur in both. 



338. The Sporophj^e.— There are several hundred 

 species of Lycopodium. Among those most common in 

 temperate America are L. clavatum (Fig. 272), L. ohscurum 



Fig. 272. — Lycopodium clavatum. 



dendroideum, and L. lucidulum. These species commonly 

 grow trailing over the surface of the ground, and from 

 this, and the appearance of their fohage, they are com- 

 monly called "ground pine," though of course they have 

 nothing to do with true pines. As is well shown in the 

 figure, the plant-body of the sporophyte of Lycopodium 

 clavatum consists of a sterile lower region, bearing foliage- 



