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PHYLUM BRYOPHYTA: 



TAXONOMIC SUMMARY 



Kingdom Plantae (Eng. plaril) — plants 



Subkingdom Embryophyta (Gr. embryon, embryo + phyton, plant) — land plants 

 Phylum Bryophyta (Gr. bryon, moss + phyton) — bryophytes 

 Class Anthocerotae (Gr. anlhos, flower + keras, horn) — horned liverworts 

 Class Hepaticae (Gr. hepar, liver) — liverworts 

 Class Musci (L. miisais, moss) — mosses 

 Order Andreales (after J. Andreae, a German apothecary) — rock or black mosses 

 Order Sphagnales (Gr. sphagnos, kind of moss) — peat mosses 

 Order Bryales (Gr. bryon) — mosses 



but also in sporophyte; processes mostly as in algae; 

 sexual reproduction limited to gametophyte and similar 

 to many algae. 



Life cycle: regularly a definite alternation of gener- 

 ations (diplobiontic life cycle) with sporophyte em- 

 bryo developing as a gametophyte parasite to gameto- 

 phyte developing as a sporophyte parasite; sporophyte 

 producing spores which develop into the gametophyte 

 — gametophyte forming male and female sex organs, 

 male organs often forming flagellate, mobile sperm, 

 and female organs forming nonflagellate eggs; fertili- 

 zation in the female sex organ; sporophyte develop- 

 ment from a fertilized egg in the female sex organ. 



Nutrition: photosynthetic, except for developing 

 sporophyte and some special types in tracheophyte 

 gametophytes; a few holozoic (saprophytic and 

 parasitic) exceptions occur. 



Occurrence: about 20,000 fresh-water, wet soil, 

 moist soil, and rock inhabiting bryophytes; about 

 200,000 mostly terrestrial but also many fresh-water 

 and a very few marine tracheophytes. 



GENER.M.IZED CELL 



Like Chlorophyta; nucleus complete and complex; 

 chlorophyll and cytoplasmic pigments in plastids; 

 flagellae, when present, limited to sperm. 



c;AMi-;roi'm iL 



Structure: typically simple, mostly a single tissue 

 layer to about three distinct tissues, and much like 

 membranous algae organization and form; in mosses 

 structure approximates that of leaves, stems, and 

 abbreviated roots, but these organs are sporophyte 

 structures; size and structure progressively reduced 

 in more complex plants to ten cells in flowering plants 

 (Class Angiospermae); sex organs multicellular in the 

 simply organized subphyla (shared only with Charo- 

 phyta) but not in the angiosperms. 



Reproduction: asexual mainly by budding and 

 fragmentation; merely slight modifications of proces- 

 ses found in algae and protists; sexual not unique, 

 involves motile, flagellate sperm and larger, non- 

 flagellate eggs in the bryophytes to more specialized 

 gametes in some tracheophytes. 



SPOROPHYTE 



Structure: unique; generally complexly organized 

 with at least two tissue types (usually more) and in- 

 cipient organ formation (Bryophyta capsule, stalk, 

 and foot) to definite organ formation (Tracheophyta 

 leaves, stems, and roots); more complex than any 

 Algae; typically differentiated into aerial parts (cap- 

 sule and stalk, or leaves and stems) and subterranean 

 parts (roots), or a part analogous to roots (foot) is 

 embedded in the gametophyte; aerial parts often 

 bearing a complex spore-forming organ, the sporan- 

 gium (bryophytes and simpler tracheophytes). .\ote: 

 Bryophyte "leaves," "stems," and "roots" when 

 present, as in mosses, are gametophyte structures 

 that are not organized as complexly as the true leaves, 

 stems, and roots (sporophyte structures) of tracheo- 

 phytes; hence calling these bryophyte structures 

 "leaves," "stems," or "roots" really is incorrect. 



Tissues: unique aspects normally include an outer 

 epidermis with scattered unique openings (stomata, 

 for gaseous exchange between the atmosphere and 

 internal tissues), each stoma bounded by two spe- 

 cialized cells (guard cells) that open and close the 

 stoma; specialized conducting tissues include the 

 columella (bryophytes) and stele (tracheophytes) and 

 usually are present; columella has thick-walled, 

 elongate cells and stele has at least xylem and phloem; 

 xylem is largely water-conducting and phloem is 

 food-conducting; stele also is called a vein or central 

 cylinder; phloem without xylem is found in the brown 

 algae (Phaeophyta). 



