Reproduction in Multicellular Planis - 213 



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TOP OF MALE 



GAMETOPHYTE 



SHOWING 



ANTHERIDIA 



TOP OF FEMALE 

 GAMETOPHYTE 



SHOWING 

 ARCHEGONIA 



•:i /H— SPORES 



SPORE 

 CAPSULE 



;->'■;;.; 



&$ 





H. 



ANTHERIDIUM 



ANTHERIDIUM 

 DISCHARGING SPERMS 



A SPERM 



W 



'H V- 



ARCHEGONIUM 



SHOWING EGG CELL 



IN VENTER 



: — SPOROPHYTE 



* 



^m 



-GAMETOPHYTE 



BOTH 

 GENERATIONS 



EMBRYO SPOROPHYTE 

 DEVELOPING IN 

 ARCHEGONIUM 



GAMETOPHYTE 

 BUD 



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DIVISION OF A 

 SPOROCYTE (MEIOSIS) 





■K" ; 



PROTONEMA WITH BUDS 



BUDS DEVELOPING INTO 



LEAVES AND STEMS 



GERMINATION OF 

 A SPORE 



Fig. 12-12. Reproductive cycle of a moss plant, typical of bryophytes generally. Be sure to differentiate be- 

 tween the haploid and diploid stages. 



However, only one sperm usually participates 

 in fertilization, which occurs in the venter 

 chamber. 



The fertilized egg marks the inception of 

 the sporophyte generation. Shortly after fer- 

 tilization this diploid cell starts its develop- 

 ment inside the archegonium of the female 

 plant. A series of mitotic divisions leads to 

 the formation of an elongate mass of cells 

 (Fig. 12-12), which is the very young em- 

 bryo sporophyte. The lower end of the 

 embryo sporophyte, which is called the foot, 

 grows downward into the stem of the parent 

 gametophyte, where it becomes firmly at- 



tached. The upper end of the embryo grows 

 more or less vertically into a long slender 

 stalk, at the top of which a hollow sporan- 

 gium finally appears (Fig. 12-12). The early 

 stages of this growth occur entirely within 

 the archegonium, which enlarges accord- 

 ingly (Fig. 12-12). But finally the stalk 

 grows so rapidly that it tears the neck, which 

 is carried aloft on the sporangium above the 

 upper leaves of the female gametophyte. 



The whole sporophyte — consisting of foot, 

 stalk, and sporangium — remains permanently 

 attached to the apex of the female game- 

 tophyte (Fig. 12-12). The exposed cells of 



