382 

Moss 
Left, a moss gametophyte bear- 
ing asporophyte; note that the 
sporangium, or capsule, is cov- 
ered by a hood, or calyptra, 
which was originally a part of 
the archegonium wall (x 12). 
Upper right, a capsule with 
calyptra removed; the upper 
portion is differentiated into a 
lid, or operculum. Below this 
figure is shown a capsule with the 
operculum removed; note the 
fringe of toothlike appendages 
known as the peristome (x 5) 
A TEXTBOOK OF GENERAL BOTANY 
Mosses are much more numerous 
than liverworts, both in species and 
in individuals, but they are much 
more uniform in structure. 
Peat mosses. Mosses are a promi- 
nent constituent of peat bogs. These 
occur in depressions containing fairly 
still water. The mosses grow in from 
the sides and form a floating mass. As 
the mosses and other plants associated 
with them continue to grow upward 
the lower layers are forced downward, 
and dead plant remains, known as peat, 
accumulate under the living cover. 
In the course of time the depression is 
filled, but the mosses, owing to their 
ability to absorb and hold large quan- 
tities of water, may continue to grow 
until the bog is raised considerably 
above its original level and even above 
the level of the surrounding area. 
The lower layers of plant remains 
become compressed and partially car- 
bonized, forming peat. The layers of 
peat are cut into blocks and used as 
fuel. The peat is sometimes treated 
so as to improve its value as a fuel. 
Coal was formed by a process some- 
what similar to that which gives rise 
to peat. The plants were different 
and their remains accumulated not in 
bogs but as muck in the Swamps or 
open waters of past ages. 
Sphagnum, the chief peat moss, is 
used extensively for packing plants 
and in surgical dressings. 
. = 
