THE BRYOPHYTES 279 



have the aquatic character of possessing ciliated sperms, 

 and water is necessary to accoinplish fertilization. 



359. Additional Notes on the Bryophytes. — The br3'o- 

 phytes are the lowest land plants which have stems and 

 leaves. Some of the lower ones, like Riccia and 3Iar- 

 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 algae 

 and fungi, and the pteridophytes, or ferns and fern-like 

 plants (Sect. 360). 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 tlie 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, ilosses, 

 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. 



