144 



ABOUT MOSSES AND LICHENS. [CHAP. 



plants which prepare a soil for the larger growths of 

 oak and pine. 



The Scale-mosses (Jungermanniacece} closely re- 

 semble the true mosses (Musci) at a superficial 

 glance, but there are many points in which they 

 differ when closely examined. In the Scale-mosses 

 the sporangia (Sp, figs. 105, 107, 108), when ripe, split 

 down the sides to allow the spores- to escape, whilst 



FIG. 106. 



FIG. 105. 



in Musci, as we have seen, they open at the top with 

 a lid. This sporange rises from a calyptra or hood 



(H, fig. 107), which is it- 

 self enclosed in a calyx 

 (cax, fig. 1 08). The spores 

 are mixed up with curious 

 spirally -twisted threads 

 (elaters, fig. 106). The cap- 

 sule or sporange splits in- 

 to four valves (V, fig. 105), 

 which fall down and allow 

 FIG 108 the dispersion of the spores. 

 A few of these plants have 



no distinction between stem and leaf, but have a 

 horizontal frond; but by far the greater number 



FIG. 107. 



