Chapter XVII. 



Christmas-green Plants or Club-mosses* 



The plants known as club-mosses are the ones so abun- 

 dantly used in the manufacture of Christmas-green decorations, 

 wreaths and festoons. Their spores are collected and sold 

 at the drug-stores under the name of lycopo- 

 dium powder, since the small, smooth, oily 

 spheres are very difficult to moisten and are 

 useful to prevent chafing. There are about 

 twelve species in Minnesota, of which some, 

 known as the smaller club-mosses or rock- 

 club-mosses, are distinguished by the posses- 

 sion of two sizes of spores, the significance of 

 which will be considered later. All Minne- 

 sota species of club-mosses are terrestrial, 

 growing particularly in the pine woods, and 

 they are known also as ground-pines. In the 

 tropics, however, and in the southern hemi- 

 sphere there are varieties of club-mosses which 

 perch upon the branches of trees and hang in 

 festoons along the trunks. 



Life-history of a club-moss. The life-his- 

 tory of the common Christmas-green club- 

 moss is somewhat as follows : The spores, 

 produced in large quantities, germinate near 

 the surface of the ground and there form di- 

 minutive sexual plants about the size of pin- 

 heads. Upon these tiny creatures the sperma- 

 ries and egg-organs are produced. The sperms 

 have two swimming-hairs like those of mosses. The gen- 

 eral structure of the spermary and egg-organ is quite like that 

 in the horned liverwort, and the sexual plant of the club-moss 

 may be compared to a horned liverwort prostrate stem very 



FIG. 49. Branch of a 

 club-moss plant, 

 bearing two cones; 

 with a single leaf of 

 the cone, showing 

 the spore case and 

 one of the spores, 

 the latter much mag- 

 nified. After Atkin- 

 son. 



