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PHYLUM BRYOPHYTA: 



L iver worts 



Mosses 



Figure 10.1 Bryophyte life cycles. Liverworts: A, mature sporophyte on gametophyte; B, spore 

 shed from sporophyte's sporangium; C, spore germinating into o gametophyte; D, mature gometophyte; 

 E, gametophyte ready to form either sex organs or cupules; F, gametophyte with cupules prepared 

 to shed gemmae; G, gemma prepared to germinate into a gametophyte; H, mature mole and female 

 gametophytes containing mature sex cells in their sex organs, the path of sperm to the female sex 

 organ (to fertilize an egg) is indicated; I, after fertilization, the fertilized egg (zygote) develops into an 

 embryo sporophyte which germinates from and remains partly within the female sex organ. 

 Mosses; 1, mature sporophyte on gametophyte (gametophore); 2, spore shed from the sporophyte's 

 sporangium; 3, sporophyte germinating into a protonemo; 4, protonemo; 5, protonema with buds 

 and immature gametophore; 6, mature gametophore; 7, mature male and female gametophores con- 

 taining mature sex cells in their sex organs, the path of sperm to the female sex organ is indicated; 

 8, after fertilization, the zygote develops into an embryo sporophyte. 



not denied by the fossil record, which implies land 

 plants became somewhat complex due to occupying 

 land habitats. Then, some of these land inhabitants 

 might have invaded coastal marshes. After some 

 time, these marsh invaders could have evolved into 

 simplified plants called psilopsids, three of which live 

 today. Therefore, if the trend toward simplification 

 continued, the product of evolution could have been 

 the bryophytes. 



The mosses are the most frequently encountered 

 bryophytes because mosses range from moist to dry 

 habitats. Typically, certain mosses are found either 

 as a developmental stage in the formation of a stable 



plant community, specifically a stage that is usually 

 intermediate between lichens and herbs, or as a layer 

 in a stable community. Liverworts and horned liver- 

 worts usually are not common because they tend to 

 be restricted to aquatic, semiaquatic, or moist areas; 

 however, in certain localities they are more common 

 than mosses. 



CLASS ANTHOCEROTAE (Horned Liverworts) 



Diagnosis: gametophyte a thin, somewhat mem- 

 branous sheet, flattened from top to bottom and 

 having embedded male and female reproductive 



