2O4 
STRUCTURE AND LIFE HISTORIES 
FIG. 147. Diagram of life-cycle of sphagnum. 
189. Other Mosses. The so-called "true mosses," 
with which we are perhaps more familar than with 
sphagnum, cannot be studied here in detail, but it may be 
said that, in broad outline, their life histories are closely 
similar to that of sphagnum. The protonema does 
not produce a thallus, but the leafy branches, or moss- 
plants, arise directly from the filamentous protonema 
(Fig. 148). They are both monoecious and dioecious. In 
the "true mosses" no pseudopodium is formed, but the 
stalk of the sporophyte (so very short in Sphagnum), 
elongates to form a seta, often over i inch iij length. In 
the spore-case, or capsule, there is much less sporogenous 
or fertile tissue, in proportion to sterile tissue, than in 
Sphagnum. Moreover, at the base of the capsules, in 
the true mosses, occur functional stomata, opening into 
intercellular spaces, and surrounded by chlorophyll- 
