418 BRYOPHYTES (MOSS PLANTS) 
spongy tissues cannot occur and are not needed until leaves be- 
come more than one cell in thickness. The stem is also quite 
simple in structure, and is not dif- 
ferentiated into the tissues which 
characterize the stems of higher 
plants. 
The sporophyte is commonly much 
larger than that of the Liverworts 
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Fic. 372.— The game- 
tophyte of a Moss, con- Fic. 373. — The two 
sisting of stem- (s) and generations of Moss. 4g, 
leaf-like structures (I), gametophyte genera- 
and rhizoids (r) which tion; a, sporophyte gen- 
attach it to the sub- eration; s, sporangium 
stratum. X about 2. of the sporophyte. 
and it can be seen usually at a considerable distance projecting 
from the top of the gametophyte. A plant bearing a sporophyte 
looks like Figure 373. 
