204 



PLANT BIOLOGY 



genus Lycopodium. They grow mostly in woods, having i -nerved 

 evergreen leaves arranged in four or more ranks. Some of them 

 make long strands, as the ground pine, and are much used for 

 Christmas decorations. The spores are all of one kind or form, 

 borne in i-celled sporangia that open on the margin into two 

 valves. The sporangia are borne in some species (Fig. 301) 



FIG. 301. A LYCOPODIUM 

 WITH SPORANGIA IN 

 THE AXII.S OF THE FO- 

 LIAGE LEAVES. (Lyco- 

 f odium lucidulum.) 



FIG. 302. A CLUB-MOSS 

 (Lycopodium complanatuni) . 



as small yellow bodies in the axils of the ordinary leaves near the 

 tip of the shoot ; in other species (Fig. 302) they are borne 

 in the axils of small scales that form a catkin-like spike. The 

 spores are very numerous, and they contain an oil that makes them 

 inflammable. About 100 species of lycopodium are known. 

 The plants grown by florists under the name of lycopodium are 

 of the genus Selaginella, more closely allied to isoetes, bearing 

 two kinds of spores (microspores and macrospores). 



