THE CLUB-MOSSES 157 



thing is known of their history in past times. 

 There are about 100 species of the genus Lycopo- 

 dium, of which five are natives of our own coun- 

 try. Four of these are plants of the moorlands 

 in hilly or mountainous districts, while one 

 (Lycopodium inundatum) is frequent hi boggy 

 places in lowland countries, as in the New Forest 

 of Hampshire. All have the habit of very large 

 mosses; the stems, which in some species reach 

 a great length, are clothed by numerous small 

 and simple leaves. In most species there are 

 definite cones, which in the Stag's Horn Moss 

 (L. clavatum) are very conspicuous and are 

 borne at the end of long, forked stalks. In L. 

 Selago, however, there is no special cone, and 

 the sporangia are produced on the ordinary 

 leaves. In all cases a single sporangium is seated 

 on the upper surface of the fertile leaf; with 

 slight variations of position this holds good for 

 all members of the class, whether homosporous 

 or heterosporous. The species, such as L. Selago, 

 in which there is no distinction between the 

 sporophylls and the vegetative leaves, are cer- 

 tainly the simpler and may be the more primitive. 

 While the plant is young the stem has a simple 

 structure, the wood forming a central column 

 with prominent angles, while the bast lies to the 

 outside. Later on, the arrangement becomes 

 more complicated, wood and bast forming alter- 



