THE BRYOPHYTES 279 
have the aquatic character of possessing ciliated sperms, 
and water is necessary to accomplish fertilization. 
359. Additional Notes on the Bryophytes. — The bryo- 
phytes are the lowest land plants which have stems and 
leaves. Some of the lower ones, like Riccia and Mar- 
chantia, have only a thallus and do not show a differentia- 
tion into stem and leaves. The bryophytes in this respect 
are intermediate between the thallus plants, such as alge 
and fungi, and the pteridophytes, or ferns and fern-like 
plants (Sect. 860). Bryophytes have no fibro-vascular bun- 
dles. They are superior to the thallus plants in the com- 
plexity of their reproductive apparatus, developing the egg 
in a many-celled archegonium. 
True roots are wanting in the bryophytes. In the liver- 
worts one-celled rhizoids and in the mosses rhizoids consist- 
ing of simple rows of cells perform the work of roots. 
Liverworts have no economic value and form but an 
insignificant part of the vegetation of the earth. Mosses, 
however, though none of them are very large plants, form 
an important part of the vegetation particularly of northern 
regions. Common mosses carpet large areas in woodlands 
and serve to prevent the rapid draining away of surface 
water after rains. In this way they help to maintain the 
constant flow of springs and rivers. Peat-mosses occur in 
immense numbers in bogs in various parts of the world. 
The dried moss is used as bedding for horses, and in a 
moist condition it is used by nurserymen and florists in 
packing plants. In extensive bogs large quantities of dead 
moss, sedges, and other plants may become accumulated 
under a layer of living plants, and the material resulting 
from their partial decay is known as peat. Dried (with or 
without compression into blocks) it is of use as fuel. 
