Chapter 11 



MOSSES AND THEIR ALLIES— BRYOPHYTES 

 (PHYLUM BRYOPHYTA) 



Intermediate Plants With Chlorophyll; Without True Leaves, 

 Stems, or Roots; Without Vascular (Conducting) Tissues; Form- 

 ing Multicellular Embryos (Subkingdom Embryophyta) 



GENERAL CHARACTERISTICS OF BRYOPHYTES 



L The members of the phylum Bryophyta (bri-of'ita) (Or. hryon^ 

 moss; phyta, plants) are terrestrial plants, although they require consid- 

 erable moisture for growth and fertilization. 



2. In general, the adult plant body of Bryophytes is composed of 

 blocks, or sheets, of cells forming a parenchymatous tissue, in contrast to 

 the simple construction of the Thallophytes. The adult plant body of 

 Bryophytes is never filamentous, but the developmental, protonema stage 

 of mosses may be filamentous. 



3. The gamete-producing sex organs, the gametangia (gam e -tan' ji a) 

 (Or. gametes, spouse or gametes; anggeion, vessel), are multicellular 

 and possess a protective layer of sterile cells, while the gametangia of 

 Thallophytes are unicellular (few exceptions). 



4. Water is required for fertilization in Bryophytes, as in most algae. 



5. All Bryophytes possess an alternation of generations between the 

 gamete-producing gametophyte generation and the spore-forming sporo- 

 phyte generation. The latter is more or less dependent on the gameto- 

 phyte. 



6. Bryophytes develop a multicellular embryo from the zygote (fer- 

 tilized t.gg) , from which the sporophyte develops. 



7. No asexual spores are produced by Bryophytes. 



8. Asexual reproduction may occur by fragmentation of the plant, or 

 by special bodies known as gemmae (jem'i) (L. gemma, bud). 



9. Bryophytes are without true vascular (conducting) tissues such as 

 phloem and xylem. 



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