BRYOPHYTES 
III 
istic of the swampy regions of higher latitudes, where they often fill up 
bogs and form peat, whence they are often called peat mosses. 
Gametophyte. The gametophyte begins as a filament (fig. 242), 
and then by means of an apical cell with two cutting faces develops 
as a simple flat thallus with rhizoids (fig. 243), just as in the simpler 
liverworts. The moss character appears 
in the development from this liverwort- 
like thallus of an upright leafy branch 
(fig. 243). This radial leafy branch, 
from a dorsi ventral body, is called vari- 
ously the adult shoot, the gametophore, 
or simply the leafy branch. The name 
gametophore is used because this branch 
FIGS. 242, 243. Sphagnum: 242, 
young gametophyte, showing the filament 
arising from the spore, a rhizoid, and 
the thallus beginning to develop by an 
apical cell ; 243, mature thallus, with 
rhizoids, producing leafy branches. 
After SCHIMPER. 
FIGS. 244, 245. Sphagnum: 244, sur- 
face view of cells of leaf, showing the 
narrow elongated cells (c) containing 
chloroplasts, and the less numerous hya- 
line cells (/) with pores (/>); 245, por- 
tion of cross section showing same 
features. 
bears the sex organs, just as in Marchantia the sex organs are borne 
on erect but leafless branches. 
The leafy branch develops by means of an apical cell with three 
cutting faces, and hence there are three vertical rows of leaves. These 
branches are densely leafy and profusely branching, forming terminal 
tufts (fig. 246). 
