THE LYCOPODIACE^. 75 



roots, penetrating the earth, give off rootlets here and 

 there as conditions require ; but in the Lycopodiums the 

 roots branch dichotomously, dividing into two equal 

 branches which may again divide in the same way. The 

 roots do not seem to have any special point on the stem 

 from which to grow, but develop on any part that 

 touches the soil. 



There are about a hundred species of Lycopodtttm 

 known at present. The majority are found in the 

 warmer regions of the world, where they often grow on 

 the branches of trees, many feet from the ground. 

 Other species clamber over the vegetation like the climb- 

 ing ferns. Our species are all low and inconspicuous 

 plants, keeping close to the earth on moors or in swamps, 

 woodlands, and thickets. Some are very hardy, electing 

 •to grow in barren rocky wastes on the very edge of the 

 world, as it were. They are often found in the greatest 

 abundance on rough mountain-tops or bordering the 

 roadsides in elevated districts. Some extend northward 

 to the Arctic Circle and beyond. All our species are 

 perennial, and not only are the leaves of most of them 

 evergreen, but many appear to last for several years. 



The lycopodiums of the present are mere rem- 

 nants of the race. During the Coal Period they were 

 most luxuriant, and the various forms attained the 

 height of trees. Of these the lepidodendrons and sigil- 

 larias are well known, while the roots of other species 

 were once erroneously referred to a genus called Stig- 

 maria. The spore-cases of some of these old lycopo- 

 diums have been so carefull}' preserved by nature that 

 their structure may still be discerned. It is a curious 

 fact that the ancient species were heterosporous, with 

 two kinds of spores like Isocies and Selaginclla, while 

 living lycopodiums have spores all alike. 



